Patent Publication Number: US-10765449-B2

Title: Endoscopic surgical device and overtube

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation application of and claims the priority benefit of a prior application Ser. No. 15/058,176, filed on Mar. 2, 2016, now allowed. The prior application Ser. No. 15/058,176 is a Continuation of PCT International Application No. PCT/JP2014/072988 filed on Sep. 2, 2014 claiming priority under 35 U.S.C. § 119(a) of U.S. Provisional Application 61/873,147 filed on Sep. 3, 2013. Each of the above applications is hereby expressly incorporated by reference, in their entirety, into the present application. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an endoscopic surgical device and an overtube (outer sleeve), and particularly, relates to an endoscopic surgical device and an overtube that can operate in a state where an endoscope and a treatment tool inserted into a body cavity are interlocked with each other. 
     2. Description of the Related Art 
     In the related art, the endoscopic surgery of inserting a treatment tool and an endoscope into a patient&#39;s body cavity and performing treatment work while observing, using the endoscope, the treatment state of an affected part using the treatment tool inserted into the body cavity has been known. In this surgery, in order for a surgeon to obtain a visual field where surgery is easy, the operation of changing the observation position of the endoscope is performed when necessary. 
     Generally, in the endoscopic surgery, a surgeon&#39;s hand is blocked due to the operation of the treatment tool, and the operation of changing the observation position of the endoscope is performed by an assistant called a scopist (endoscopic technician). For this reason, when the observation position of the endoscope is changed, the surgeon should serially give instructions to the assistant. Therefore, the work of correctly directing the orientation of the endoscope to a direction desired by the surgeon is difficult, and stress is likely to be imposed on the surgeon. Additionally, since the assistant performs an operation after the surgeon issues an instruction, there is a tendency that surgery time is likely to be prolonged. Additionally, the assistant should operate the endoscope so as not to interfere with a surgeon&#39;s procedure, and the operation is likely to become complicated. 
     In contrast, various techniques of interlocking the endoscope and the treatment tool have been suggested up to now (for example, refer to JP2004-141486A and JP2003-325436A). 
     An endoscopic surgery system that moves the treatment tool while following the fluctuation of the visual field of the endoscope is disclosed in JP2004-141486A. In this endoscopic surgery system, a treatment part of the treatment tool is kept from deviating from the visual field of the endoscope by detecting the movement distance (the rotational angle and the amount of insertion and extraction) of the endoscope in a state where the endoscope and the treatment tool have been inserted into an integral sheath (guide member), and controlling the movement distance (the rotational angle and the amount of insertion and extraction) of the treatment tool with respect to the sheath on the basis of the detection result. 
     Additionally, an endoscopic surgery device that changes the visual field of the endoscope while following the movement of the treatment tool inserted into the body cavity during the endoscopic surgery is disclosed in JP2003-325436A. This endoscopic surgery device is provided by mechanically coupling the treatment tool to a distal end part of the endoscope to integrally move the treatment tool and the distal end part of the endoscope to move the observation optical axis of the endoscope in a direction in which the treatment tool moves. 
     SUMMARY OF THE INVENTION 
     Under the above background, in the endoscopic surgery, it is desired that the visual field of the endoscope can be easily changed while the surgeon operates the treatment tool without asking for an assistant&#39;s help. 
     However, the endoscopic surgery system disclosed in JP2004-141486A does not mechanically interlock the endoscope with the treatment tool, and has a problem in which a mechanism for performing interlocking control of the endoscope and the treatment tool is easily enlarged and complicated. Additionally, this endoscopic surgery system moves the treatment tool while following the movement of the endoscope, and does not move the endoscope while following the movement of the treatment tool. For this reason, there are problems in that it is necessary to ask for an assistant&#39;s help in order to change the visual field of the endoscope, the operation for changing the observation position of the endoscope as intended by a surgeon easily becomes complicated, and the surgery time is easily prolonged. 
     Additionally, since the endoscopic surgery device disclosed in JP2003-325436A has a configuration in which the endoscope and the treatment tool are mechanically coupled and always move integrally, the visual field of the endoscope also changes minutely in an interlocking manner with minute movement of the treatment tool. For this reason, there is a problem in that an observation image obtained by the endoscope moves minutely and is hardly seen. Particularly when the endoscope and the treatment tool are inserted into the body cavity in a parallel state, there is a problem in which the size of an object to be observed changes in an interlocking manner with the minute movement of the treatment tool, and a sense of perspective cannot be easily held. 
     Additionally, JP2004-141486A and JP2003-325436A neither disclose nor suggest the terms and conditions for interlocking the forward and backward movement of the treatment tool with the forward and backward movement of the endoscope. 
     In this way, in any of the related-art techniques, there are various problems in order to smoothly perform the endoscopic surgery, and it cannot be said that the techniques of interlocking the endoscope and the treatment tool inserted into the body cavity are sufficient. 
     The invention has been made in view of such a situation and an object thereof is to provide an endoscopic surgical device and an overtube with which a surgeon can easily obtain a desired image with simple operation without increasing a burden on the surgeon. 
     In order to achieve the above object, an endoscopic surgical device related to a first aspect of the invention is an endoscopic surgical device including an endoscope that observes the inside of a body cavity; a treatment tool that inspects or treats an affected part within the body cavity; and an overtube that guides the endoscope and the treatment tool into the body cavity. The overtube includes an overtube body that passes through a body wall and is inserted into the body cavity, an endoscope insertion passage that is provided inside the overtube body and allows the endoscope to be inserted therethrough so as to be movable forward and backward, a treatment tool insertion passage that is provided inside the overtube body and allows the treatment tool to be inserted therethrough so as to be movable forward and backward, and an interlocking member that is configured to be movable forward and backward inside the overtube body, has an endoscope-coupled part coupled to the endoscope inserted through the endoscope insertion passage and a treatment tool-coupled part coupled to the treatment tool inserted through the treatment tool insertion passage, and has a dead zone where the forward and backward movement of either the endoscope or the treatment tool does not interlock with the movement of the other and a sensing zone where the forward and backward movement of either the endoscope or the treatment tool interlocks with the movement of the other. The following formula is satisfied when a fixing force for fixing the endoscope-coupled part to the endoscope is defined as F1 and a fixing force for fixing the treatment tool-coupled part to the treatment tool is defined as F2.
 
 F 1 &gt;F 2
 
     In the first aspect of the invention, it is preferable that the endoscopic surgical device further includes a first valve member that is provided in the endoscope insertion passage and secures airtightness within the body cavity; and a second valve member that is provided in the treatment tool insertion passage and secures airtightness within the body cavity, and the following formula is satisfied when a frictional force that the endoscope receives from the first valve member when the endoscope moves forward and backward is defined as F3.
 
 F 1&gt; F 3
 
 F 2&gt; F 3
 
     Additionally, in the first aspect of the invention, it is preferable that the coupling position is set so as to satisfy the following formula when the length from a coupling position of the endoscope to which the endoscope-coupled part is coupled to the distal end position of the overtube body in the axial direction of the overtube body is defined as L and the length from the coupling position to a distal end position of the endoscope in the axial direction of the overtube body is defined as Ls, in a state where the interlocking member has moved to a position closest to a base end position of a movable range thereof.
 
 Ls≥L  
 
     Additionally, in the first aspect of the invention, it is preferable that the interlocking member includes a slider member that is coupled to the endoscope and moves forward and backward integrally with the endoscope, and a sleeve member that is coupled to the treatment tool and moves forward and backward integrally with the treatment tool, and a range where the sleeve member is movable forward and backward with respect to the slider member is limited. 
     Additionally, an overtube related to a second aspect of the invention is an overtube including an overtube body that passes through a body wall and is inserted into a body cavity; an endoscope insertion passage that is provided inside the overtube body and allows an endoscope for observing the inside of the body cavity to be inserted therethrough so as to be movable forward and backward; a treatment tool insertion passage that is provided inside the overtube body and allows a treatment tool for inspecting or treating an affected part within the body cavity to be inserted therethrough so as to be movable forward and backward; and an interlocking member that is configured to be movable forward and backward inside the overtube body, has an endoscope-coupled part coupled to the endoscope inserted through the endoscope insertion passage and a treatment tool-coupled part coupled to the treatment tool inserted through the treatment tool insertion passage, and has a dead zone where the forward and backward movement of either the endoscope or the treatment tool does not interlock with the movement of the other and a sensing zone where the forward and backward movement of either the endoscope or the treatment tool interlocks with the movement of the other. The following formula is satisfied when a fixing force for fixing the treatment endoscope-coupled part to the endoscope is defined as F1 and a fixing force for fixing the treatment tool-coupled part to the treatment tool is defined as F2.
 
 F 1&gt; F 2
 
     Additionally, in the overtube related to the second aspect of the invention, it is preferable that the overtube further includes a first valve member that is provided in the endoscope insertion passage and secures airtightness within the body cavity; and a second valve member that is provided in the treatment tool insertion passage and secures airtightness within the body cavity, and the following formulas are satisfied when a frictional force that the endoscope receives from the first valve member when the endoscope moves forward and backward is defined as F3.
 
 F 1&gt; F 3
 
 F 2&gt; F 3
 
     Additionally, in the overtube related to the second aspect of the invention, it is preferable that the coupling position is set so as to satisfy the following formula when the length from a coupling position of the endoscope to which the endoscope-coupled part is coupled to the distal end position of the overtube body in the axial direction of the overtube body is defined as L and the length from the coupling position to a distal end position of the endoscope in the axial direction of the overtube body is defined as Ls, in a state where the interlocking member has moved to a position closest to a base end position of a movable range thereof.
 
 Ls≥L  
 
     Additionally, in the overtube related to the second aspect of the invention, it is preferable that the interlocking member includes a slider member that is coupled to the endoscope and moves forward and backward integrally with the endoscope, and a sleeve member that is coupled to the treatment tool and moves forward and backward integrally with the treatment tool, and a range where the sleeve member is movable forward and backward with respect to the slider member is limited. 
     According to the invention, since the fixing force (F1) for fixing the endoscope-coupled part to the endoscope is made larger than the fixing forces (F2) of the treatment tool-coupled part to the treatment tool, a surgeon can move the endoscope forward and backward in an interlocking manner with the forward and backward movement of the endoscope if the treatment tool is moved forward and backward without asking for an assistant&#39;s help. Additionally, the endoscope moves forward and backward with play with respect to the forward and backward movement of the treatment tool. Thus, when the treatment tool has been minutely displaced in the axial direction (when a forward and backward movement of a small amplitude has been performed), the size of an object to be observed can be prevented from fluctuating, a sense of perspective can be suitably maintained, and a stable observation image can be provided. Additionally, when the treatment tool has been largely displaced in the axial direction (when a forward and backward movement of a large amplitude has been performed), the range of an observation image obtained by the endoscope is changed in an interlocking manner with this large displacement. Thus, the size of an object to be observed changes according to the operation of the treatment tool, and it is possible to simply obtain an image desired by a surgeon, and operability improves. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic configuration diagram of an endoscopic surgical device related to the invention. 
         FIG. 2  is a plan view illustrating a distal end surface of an endoscope insertion part. 
         FIG. 3  is an external appearance perspective view illustrating an overtube from the rear upper left. 
         FIG. 4  is a sectional view, as seen from arrow  4 - 4  of  FIG. 3 , illustrating the internal structure of the overtube. 
         FIG. 5  is a sectional view of the periphery of a base end cap cut in a plane orthogonal to a paper surface of  FIG. 4 . 
         FIG. 6  is an enlarged sectional view illustrating a portion of  FIG. 4  in an enlarged manner. 
         FIG. 7  is a sectional view as seen from arrow  7 - 7  in  FIG. 6 . 
         FIG. 8  is a perspective view illustrating a slider from the rear upper left. 
         FIG. 9  is a perspective view illustrating the slider from the rear upper right. 
         FIG. 10  is a sectional view of the slider. 
         FIG. 11  is an explanatory view used for the description of the action of the slider. 
         FIG. 12  is an explanatory view used for the description of the action of the slider. 
         FIG. 13  is an explanatory view used for the description of the action of the slider. 
         FIG. 14  is an explanatory view used for the description of the action of the slider. 
         FIG. 15  is a sectional view illustrating another embodiment of the supporting mechanism of the slider in the overtube. 
         FIG. 16  is a sectional view illustrating another embodiment of the supporting mechanism of the slider in the overtube. 
         FIG. 17  is a sectional view of the overtube illustrating a state where a slider body has been arranged at a rear end of a movable range. 
         FIG. 18  is a plan view illustrating an embodiment of an endoscope that can prevent the distal end of the endoscope insertion part from entering the overtube. 
         FIG. 19  is a sectional view illustrating a portion of the overtube immediately after a slider has been coupled to the endoscope insertion part of  FIG. 18  in an enlarged manner. 
         FIG. 20  is a plan view illustrating the embodiment of the endoscope that can prevent the distal end of the endoscope insertion part from entering the overtube. 
         FIG. 21  is a perspective view illustrating a state where an inner needle has been mounted on the overtube, from the front upper left. 
         FIG. 22  is a perspective view illustrating a state where the inner needle has been mounted on the overtube, from the rear lower left. 
         FIG. 23  is a perspective view illustrating the inner needle from the front lower left. 
         FIG. 24  is a perspective view illustrating a situation in which the inner needle is mounted on the overtube. 
         FIGS. 25A to 25C  are views illustrating a situation in which the overtube is inserted into a body wall. 
         FIGS. 26A and 26B  are views illustrating a situation in which the treatment tool insertion part is pushed into the affected part side within the body cavity from the hand side. 
         FIGS. 27A and 27B  are views illustrating a situation in which the treatment tool insertion part is pushed into the affected part side within the body cavity from the hand side. 
         FIGS. 28A and 28B  are views illustrating a situation in which the treatment tool insertion part is pulled to the hand side from the affected part side within the body cavity. 
         FIGS. 29A and 29B  are views illustrating a situation in which the treatment tool insertion part is pulled to the hand side from the affected part side within the body cavity. 
         FIG. 30  is a view illustrating a port arrangement in laparoscopic gallbladder removal surgery. 
         FIG. 31  is a view illustrating the procedure of the laparoscopic gallbladder removal surgery. 
         FIG. 32  is a view illustrating a procedure of a gallbladder treatment step. 
         FIG. 33  is a schematic view illustrating a situation in which laparoscopic kidney removal procedure is performed. 
         FIG. 34  is a schematic view illustrating a situation in which the laparoscopic kidney removal procedure is performed. 
         FIG. 35  is a view illustrating a procedure of laparoscopic kidney removal surgery. 
         FIG. 36  is a view illustrating a procedure of a kidney treatment step. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A preferred embodiment of the invention will be described below in detail according to the accompanying drawings. In addition, any drawing may illustrate main parts in an exaggerated manner for description, and may have dimensions different from actual dimensions. 
     &lt;Configuration of Endoscopic Surgical Device&gt; 
       FIG. 1  is a schematic configuration diagram of an endoscopic surgical device related to the invention. As illustrated in  FIG. 1 , an endoscopic surgical device  10  includes an endoscope  100  that observes the inside of a patient&#39;s body cavity, a treatment tool  200  for inspecting or treating an affected part within the patient&#39;s body cavity, and an overtube  300  (guide member) that guides the endoscope  100  and the treatment tool  200  into the body cavity. 
     &lt;Configuration of Endoscope&gt; 
     The endoscope  100  includes an elongated insertion part (hereinafter referred to as “endoscope insertion part”)  102  that is, for example, a hard endoscope, such as a laparoscope, and that is inserted into a body cavity, and an operating part  104  that is provided continuously with a base end side of the endoscope insertion part  102 . A universal cable  106  is connected to the operating part  104 , and each of a processor device  108  and a light source device  110  is detachably connected to a distal end part of the universal cable  106  via a connector (not illustrated). Additionally, the processor device  108  is connected to a monitor  112  via a cable. 
     As illustrated in  FIG. 2 , a distal end surface  114  of the endoscope insertion part  102  is provided with an observation window  116  and illumination windows  118  and  118 . 
     An objective lens of an observation optical system, and image pick-up elements, such as a charge-coupled device (CCD) and a complementary metal-oxide semiconductor (CMOS), which are arranged at an image pick-up position of the objective lens, are disposed behind the observation window  116 . A signal cable (not illustrated) is connected to a substrate that supports the image pick-up element. The signal cable is inserted through the endoscope insertion part  102 , the operating part  104 , and the universal cable  106 , and the like of  FIG. 1 , is provided to extend up to the connector (not illustrated), and is connected to the processor device  108 . An observation image picked up by the observation window  116  is formed on a light-receiving surface of the image pick-up element, and is converted into electrical signals (image pick-up signals), and the electrical signals are output to the processor device  108  via the signal cable and are converted into video signals. Then, the video signals are output to the monitor  112  connected to the processor device  108 , and the observation image (endoscope image) is displayed on a screen of the monitor  112 . 
     An exit end of a light guide (not illustrated) is disposed behind the illumination windows  118  and  118  of  FIG. 2 . The light guide is inserted through the endoscope insertion part  102 , the operating part  104 , and the universal cable  106  of  FIG. 1  and has an incident end disposed within the connector (not illustrated). Therefore, by coupling the connector to the light source device  110 , the illumination light radiated from the light source device  110  is transmitted to the illumination windows  118  and  118  via the light guide, and is radiated forward from the illumination windows  118  and  118 . In addition, in  FIG. 2 , the two illumination windows  118  and  118  are disposed on the distal end surface  114  of the endoscope insertion part  102 . However, the number of the illumination windows  118  is not limited, and the number thereof may be one or three or more. 
     &lt;Configuration of Treatment Tool&gt; 
     As illustrated in  FIG. 1 , the treatment tool  200  consists of, for example, forceps, and includes an elongated insertion part (hereinafter referred to as a “treatment tool insertion part”)  202  that is inserted into a body cavity, an operating part  204  that is provided on the base end side of the treatment tool insertion part  202  and is gripped by a surgeon, and a treatment part  206  that is provided on a distal end side of the treatment tool insertion part  202  and is operable by the operation of the operating part  204 . 
     The treatment tool insertion part  202  is provided with a tubular sheath  208 , and an operating shaft (not illustrated) that is inserted into the sheath  208  so as to be movable in the direction of an axial center. Moreover, the operating part  204  is provided with a fixed handle  210 , and a movable handle  214  that is rotatably coupled to the fixed handle  210  via a turning pin. A base end part of the operating shaft is coupled to the movable handle  214 . 
     The treatment part  206  is provided with a pair of gripping members capable of being openable and closable. The gripping members are coupled to a distal end part of the operating shaft via a driving mechanism (not illustrated). With the rotational operation of the movable handle  214  of the operating part  204 , the gripping members of the treatment part  206  are opened and closed via the operating shaft and the driving mechanism. 
     In addition, the treatment tool  200  is not limited to the forceps, and may be, for example, other treatment tools, such as a laser probe, a suture device, an electric scalpel, a needle holder, and an ultrasonic aspirator. 
     &lt;Configuration of Overtube&gt; 
       FIG. 3  is an external appearance perspective view illustrating the overtube  300  from the rear upper left. 
     As illustrated in this drawing, the overtube  300  has an endoscope insertion passage  306  through which the endoscope insertion part  102  of the endoscope  100  is inserted so as to be movable forward and backward, and a treatment tool insertion passage  308  through which the treatment tool insertion part  202  of the treatment tool  200  is inserted so as to be movable forward and backward. 
     The endoscope insertion passage  306  has a diameter such that at least the endoscope insertion part  102  is capable of being inserted therethrough, using an endoscope insertion axis  306   a , which is parallel to a reference axis  300   a  (longitudinal axis) indicating a central axis of the entire overtube  300 , as a central axis, and indicates a space portion within the overtube  300  that penetrates from a base end surface  302  of the overtube  300  to a distal end surface  304  thereof. The endoscope insertion axis  306   a  is equivalent to the position of the axis (central axis) of the endoscope insertion part  102  that is inserted through the endoscope insertion passage  306 . 
     The base end surface  302  is provided with an endoscope insertion opening  310  for allowing the endoscope insertion part  102  to be inserted into the endoscope insertion passage  306  therethrough, and the distal end surface  304  is provided with an endoscope delivery opening  312  for allowing the endoscope insertion part  102  inserted into the endoscope insertion passage  306  to be delivered to the outside therethrough. 
     The treatment tool insertion passage  308  has a diameter such that at least the treatment tool insertion part  202  is capable of being inserted therethrough, using a treatment tool insertion axis  308   a  parallel to the reference axis  300   a  as a central axis, and indicates a space portion within the overtube  300  that penetrates from the base end surface  302  of the overtube  300  to the distal end surface  304 . The treatment tool insertion axis  308   a  is equivalent to the position of the axis (central axis) of the treatment tool insertion part  202  that is inserted through the treatment tool insertion passage  308 . 
     The base end surface  302  is provided with a treatment tool insertion opening  314  for allowing the treatment tool insertion part  202  to be inserted into the treatment tool insertion passage  308  therethrough, and the distal end surface  304  is provided with a treatment tool delivery opening  316  for allowing the treatment tool insertion part  202  inserted into the treatment tool insertion passage  308  to be delivered to the outside therethrough. 
     Additionally, the overtube  300  has an air supply connector  318  (fluid-supplying connector) on the base end surface  302 . The air supply connector  318  is provided at the end part of an air supply pipe line that communicates with the endoscope insertion passage  306  and the treatment tool insertion passage  308  inside the overtube  300 . 
     One end part of an air supply tube  122  (tube member) illustrated in  FIG. 1  is connected to the air supply connector  318 , and the other end part of the air supply tube  122  is connected to a pneumoperitoneum device  120 . Therefore, if pneumoperitoneum gas (gas for pneumoperitoneum), such as carbon dioxide gas, is supplied from the pneumoperitoneum device  120  to the air supply tube  122 , the pneumoperitoneum gas is sent from the air supply connector  318  to the inside of the overtube  300 , and is delivered from the endoscope delivery opening  312  and the treatment tool delivery opening  316  of the distal end surface  304  through the inside of the overtube  300  to the outside of the overtube  300 . 
     In addition, regarding the position and orientation of a space where the overtube  300  has been arranged, terms called front, rear, left, right, up, and down are used with the orientation from the base end surface  302  in a direction along the reference axis  300   a  to the distal end surface  304  defined as the front and with the orientation from the reference axis  300   a  to the endoscope insertion axis  306   a  defined as the left. 
     (Internal Structure of Overtube) 
     The specific configuration of the overtube  300  will be described.  FIG. 4  is a sectional view (a sectional view as seen from arrow  4 - 4  of  FIG. 3 ) illustrating the internal structure of the overtube  300 , and illustrates a section cut in a plane that includes the reference axis  300   a  and orthogonal to an upward-downward direction. In the present specification, when a drawing is simply called a sectional view, the drawing illustrates a sectional view cut by the same plane as  FIG. 4 . 
     As illustrated in this drawing, the overtube  300  has an overtube body  320  that occupies substantially the entire area in a forward-rearward direction, a base end cap  340  that is arranged at a rear part of the overtube  300 , a distal end cap  360  that is arranged at a distal end part, and a slider  400  (interlocking member) that is arranged inside the overtube  300 . In addition, the base end cap  340  and the distal end cap  360  are some of the constituent elements of the overtube body of the invention, and may be formed separately from or formed integrally with the overtube body  320 . 
     (Description of Overtube Body) 
     The overtube body  320  is formed in an elongated cylindrical shape having the reference axis  300   a  as a central axis using hard resin, metal, or the like, and has an outer wall  322  that surrounds an outer periphery, and a lumen  324  that penetrates from a base end of the overtube body  320  to a distal end thereof. 
     The lumen  324  has the endoscope insertion axis  306   a  and the treatment tool insertion axis  308   a  inserted therethrough, and is provided with a space that serves as the endoscope insertion passage  306  and the treatment tool insertion passage  308 . 
     Additionally, the lumen  324  serves as the air supply pipe line through which the pneumoperitoneum gas sent in from the air supply connector  318  passes. 
     The base end cap  340  is attached to the base end of the overtube body  320 , and is formed in a columnar shape made to have a larger diameter than the external diameter of the overtube body  320 , using hard resin, metal, or the like. The base end cap  340  has a flat rear end surface serving as the base end surface  302  of the overtube  300  on the rear side thereof, and has through-holes  342  and  344  that penetrate from the base end surface  302  to the lumen  324  of the overtube body  320 . 
     The through-hole  342  has a central axis arranged coaxially with the endoscope insertion axis  306   a , and forms a portion of the endoscope insertion passage  306 . An opening of the through-hole  342  in the base end surface  302  is equivalent to the above-described endoscope insertion opening  310 . 
     The through-hole  344  has a central axis arranged coaxially with the treatment tool insertion axis  308   a , and forms a portion of the treatment tool insertion passage  308 . An opening of the through-hole  344  in the base end surface  302  is equivalent to the above-described treatment tool insertion opening  314 . 
     Valve members  346  and  348  (a first valve member  346 , a second valve member  348 ) are respectively arranged in the through-hole  342  and the through-hole  344 . Although the detailed description of the valve members  346  and  348  is omitted, the valve members have, for example, slits that open only when being inserted through the endoscope insertion part  102  and the treatment tool insertion part  202  and that come into close contact with outer peripheral surfaces (side surfaces) of the endoscope insertion part  102  and the treatment tool insertion part  202  without a substantial gap. This secures the airtightness of spaces closer to the distal end side than the valve members  346  and  348 , and reduces the leakage or the like of the pneumoperitoneum gas injected into the body cavity to the outside of the body. 
     In addition, the valve members  346  and  348  are not limited to those with the specific configuration, and valve members with widely-known arbitrary configurations can be used. Although  FIG. 4  illustrates a configuration in which the two valve members are respectively arranged in the through-hole  342  and the through-hole  344 , a configuration in which one valve member or three or more valve members are arranged may be adopted. 
     (Description of Air Supply Connector) 
     Additionally,  FIG. 5  is a sectional view of the periphery of the base end cap  340  when the overtube  300  is cut in a plane that includes the reference axis  300   a  and is orthogonal to the paper surface of  FIG. 4 . As illustrated in this drawing, the base end cap  340  has a through-hole  350  that penetrates from the base end surface  302  to the lumen  324  of the overtube body  320 . 
     The through-hole  350  is a portion of the air supply pipe line that allows the pneumoperitoneum gas to flow therethrough, and has a rear end part formed at a position below the reference axis  300   a . The rear end part is provided with the above-described air supply connector  318  to which the air supply tube  122  (refer to  FIG. 1 ) from the pneumoperitoneum device  120  is connected. 
     The air supply connector  318  is formed in an elongated cylindrical shape, and has a part buried and fixed inside the through-hole  350 . Accordingly, at a position below the reference axis  300   a  in the base end surface  302 , the axis (central axis) of the air supply connector  318  is arranged so as to be substantially orthogonal to the base end surface  302  (arranged parallel to the reference axis  300   a ), and the air supply connector  318  is provided to protrude rearward from the base end surface  302 . 
     The air supply tube  122  is connected to the air supply connector  318  by fitting the air supply tube  122  to the outer periphery of the air supply connector  318 . Then, if the pneumoperitoneum gas is delivered from the pneumoperitoneum device  120  to the air supply tube  122 , the pneumoperitoneum gas is sent into the lumen  324  of the overtube body  320  from the air supply connector  318 . 
     (Merits Based on Arrangement of Air Supply Connector on Base End Surface) 
     Here, in an overtube that guides one medical instrument into a body cavity, it is general that the air supply connector is provided not on a base end surface of the overtube but on a side surface thereof. 
     This is because the air supply connector may interfere with an inner needle supposing that the air supply connector is provided on the base end surface, and because the overtube can be rotated around the axis so as to prevent the interference of the air supply connector and the air supply tube with a body wall without influencing the position of the medical instrument inserted through the overtube even if the air supply connector is provided on the side surface. 
     On the other hand, in the overtube  300  of the present embodiment, if the overtube  300  is rotated around the axis, the position of the endoscope insertion part  102  and the treatment tool insertion part  202  changes. Therefore, a case where it is difficult to avoid any interference of the air supply connector  318  and the air supply tube  122  with the body wall while maintaining the positions of the endoscope insertion part  102  and the treatment tool insertion part  202  within the body cavity at positions desired by a surgeon may occur. 
     Thus, in the overtube  300  of the present embodiment, the interference of the air supply connector  318  and the air supply tube  122  with the body wall is prevented by arranging the air supply connector  318  on the base end surface  302  of the overtube  300 , and the interference of the air supply tube with the inner needle is avoided by devising the configuration of the inner needle as will be described below. 
     In addition, the air supply pipe line within the air supply connector  318  and the overtube  300  may be provided in order to supply fluids other than the pneumoperitoneum gas into a body cavity. 
     The distal end cap  360  illustrated in  FIG. 4  is attached to the distal end of the overtube body  320 , and is formed of hard resin, metal, or the like. The distal end cap  360  has a front surface serving as the distal end surface  304  of the overtube  300  on a front side thereof, and has through-holes  362  and  364  that penetrate from the lumen  324  of the overtube body  320  to the distal end surface  304 . 
     The through-hole  362  has a central axis arranged coaxially with the endoscope insertion axis  306   a , and forms a portion of the endoscope insertion passage  306 . An opening of the through-hole  362  in the distal end surface  304  is equivalent to the above-described endoscope delivery opening  312 . 
     The through-hole  364  has a central axis arranged coaxially with the treatment tool insertion axis  308   a , and forms a portion of the treatment tool insertion passage  308 . An opening of the through-hole  364  in the distal end surface  304  is equivalent to the above-described treatment tool delivery opening  316 . 
     Additionally, as described above, the pneumoperitoneum gas sent into the lumen  324  of the overtube body  320  via the air supply tube  122 , the air supply connector  318  of the base end cap  340 , and the through-hole  350  from the pneumoperitoneum device  120  is delivered to the outside (the inside of a body cavity) via the through-hole  362  and the through-hole  364 . 
     Although the overtube body  320 , the base end cap  340 , and the distal end cap  360  above form the outer wall of the overtube  300 , the outer wall of the overtube  300  may not necessarily be constituted of these separated members. 
     The air supply pipe line of the overtube body  320  through which the pneumoperitoneum gas passes may be a lumen that is provided separately from the lumen  324 . 
     (Description of Slider) 
     Next, the slider  400  will be described. 
     The slider  400  illustrated in  FIG. 4  is housed within the lumen  324  of the overtube body  320 , and is supported so as to be movable forward and backward in the direction of the reference axis  300   a.    
     The slider  400  is an interlocking member that is coupled to the endoscope insertion part  102  inserted through the endoscope insertion passage  306  and the treatment tool insertion part  202  inserted through the treatment tool insertion passage  308  and that has a dead zone where the forward and backward movement of either the endoscope insertion part or the treatment tool insertion part in the forward-rearward direction (axial direction) does not interlock with the movement of the other and a sensing zone where the forward and backward movement of either the endoscope insertion part or the treatment tool insertion part interlocks with the movement of the other. 
     That is, the endoscope insertion part  102  is adapted to interlock with the forward and backward movement of the treatment tool insertion part  202  in the axial direction with play. 
     Accordingly, when a surgeon has moved the treatment tool insertion part  202  forward and backward in the axial direction and when the axial displacement of the treatment tool insertion part  202  is large (when a forward and backward movement of a large amplitude has been performed), the endoscope insertion part  102  also moves in an interlocking manner forward, backward, upward, downward, rightward, and leftward. Thus, the visual field, orientation, and the like of the endoscope  100  can be changed as intended by a surgeon. 
     Additionally, the visual field is always given to pick up an image of a treatment tool distal end, and consequently, an image that is optimal for treatment is automatically provided. When it is desired to check places other than the treatment part, the checking can be performed by moving forceps, and a surgeon can perform operations as desired. Therefore, an assistant (scopist) who operates the endoscope  100  apart from the surgeon can be made unnecessary, and a troublesome condition in which the surgeon should instruct an assistant about the visual field, orientation, and the like of the endoscope serially can be eliminated. 
     Additionally, when the axial displacement of the treatment tool insertion part  202  is small (when a forward and backward movement of a small amplitude has been performed), the endoscope insertion part  102  does not interlock. Therefore, the size of an object to be observed within an observation image can be prevented from fluctuating unnecessarily, a sense of perspective can be suitably maintained, and a stable observation image can be provided. 
     (Internal Structure of Slider) 
     The internal structure of the slider  400  will be described. 
       FIG. 6  is an enlarged sectional view illustrating a portion, in which the slider  400  is arranged in  FIG. 4 , in an enlarged manner, and illustrates a state where the endoscope insertion part  102  and the treatment tool insertion part  202  have been inserted through the endoscope insertion passage  306  and the treatment tool insertion passage  308 , respectively. 
       FIG. 7  is a view as seen from arrow  7 - 7  in  FIG. 6 . 
     Additionally,  FIGS. 8 and 9  are respectively perspective views illustrating the slider  400  from the rear upper left and from the rear upper right and  FIG. 10  is a sectional view of only the slider  400 . 
     As illustrated in  FIGS. 6 to 10 , the slider  400  has a slider body  402  (slider member) that holds components of the slider  400 . The slider body  402 , as illustrated in  FIGS. 7 to 9 , has a flat upper surface  404  and a flat lower surface  406 , and has protruding strips  408  and  410 , respectively, on the upper surface  404  and the lower surface  406 . 
     The protruding strips  408  and  410  respectively protrude in the upward-downward direction at substantially central parts of the upper surface  404  and the lower surface  406  in a leftward-rightward direction, extend in the direction (forward-rearward direction) of the reference axis  300   a  within the lumen  324  of the overtube body  320 , and are fitted into guide grooves  370  and  372  provided in an upper part and a lower part within the lumen  324  of the overtube body  320  as illustrated in  FIG. 7 . 
     The guide grooves  370  and  372  are respectively formed by gaps between a pair of left and right guide plates  374  and  374  and a pair of left and right the guide plates  376  and  376  that are arranged at the upper part and the lower part within the lumen  324 . 
     The guide plates  376  and  376  arranged at the lower part within the lumen  324  are illustrated in  FIG. 4 . As illustrated in this drawing, the guide plates  374  and  374  and the guide plates  376  and  376  are respectively formed in the shape of a long plate, and are installed along the direction of the reference axis  300   a  by being laid between the base end cap  340  and the distal end cap  360 . 
     Accordingly, the guide grooves  370  and  372  are respectively arranged along the direction of the reference axis  300   a  from the base end cap  340  to the distal end cap  360  within the lumen  324 . 
     As illustrated in  FIG. 7 , in a state where the slider  400  is housed and arranged within the lumen  324 , the protruding strips  408  and  410  are respectively fitted into the guide grooves  370  and  372 , and the upper surface  404  and the lower surface  406  respectively contact or approach the guide plates  374  and  374  and the guide plates  376  and  376 . Accordingly, the slider  400  (slider body  402 ) is supported so as to be movable forward and backward in the forward-rearward direction within the lumen  324 , and is supported in a state where the movement of the slider in the upward-downward direction and in the leftward-rightward direction and the rotation of the slider in all directions are restricted (a state where the rotation of the slider around at least the reference axis  300   a  is impossible). 
     In addition, the guide grooves  370  and  372  may not be formed by the guide plates  374  and  374  and the guide plates  376  and  376  arranged within the lumen  324  of the overtube body  320 , and may be formed in the outer wall  322  of the overtube body  320  or may be formed by other configurations. 
     Additionally, a range (movable range) in which the slider  400  (slider body  402 ) moves forward and backward in the forward-rearward direction with respect to the overtube body  320  is a range having a position where the slider  400  abuts against the base end cap  340  as a rear end (a position closest to the base end) and having a position where the slider abuts against the distal end cap  360  as a front end (a position closest to the distal end). However, the rear end and the front end of the movable range of the slider  400  may not be restricted by the base end cap  340  and the distal end cap  360 . 
     Additionally, the slider  400 , as illustrated in  FIG. 10 , has an endoscope-coupled part  420  that is coupled (engaged) with the endoscope insertion part  102 , and a treatment tool-coupled part  422  that is coupled (engaged) with the treatment tool insertion part  202 . 
     (Description of Endoscope-Coupled Part) 
     The endoscope-coupled part  420  is provided on the left side of the slider body  402 , and includes a through-hole  424  in which a space serving as the endoscope insertion passage  306  is secured within the lumen  324  of the overtube body  320  and through which, as illustrated in  FIG. 6 , the endoscope insertion part  102  is inserted, and a pressure-contact member  426  that is brought into pressure contact with the outer peripheral surface (side surface) of the endoscope insertion part  102  inserted through the endoscope insertion passage  306 . 
     The through-hole  424  is formed to penetrate from a rear end of the slider body  402  to a front end thereof, and has a larger diameter than the external diameter of at least the endoscope insertion part  102 . A central axis of the through-hole  424  is arranged coaxially with the endoscope insertion axis  306   a  within the lumen  324 . 
     A pressure-contact member attachment part  428  for attaching the pressure-contact member  426  is provided on the rear end side of the through-hole  424 . 
     The pressure-contact member attachment part  428  has an internal diameter that is made larger than other position ranges of the through-hole  424 , and has formed therein an opening  430  (refer to  FIG. 8 ) that penetrates up to an outer surface (left side surface  431 ) of the slider body  402  in a partial range thereof (a left side surface of the slider  400 ) in the circumferential direction. The pressure-contact member  426  is fitted into the through-hole  424  from the opening  430 , and the pressure-contact member  426  is fixed to the slider body  402  in the pressure-contact member attachment part  428 . 
     The pressure-contact member  426 , as illustrated in  FIG. 7 , is annularly formed of an elastic material, such as elastic rubber or a spring, and a central axis of a through-hole  432  thereof is arranged coaxially with the endoscope insertion axis  306   a.    
     Accordingly, when the endoscope insertion part  102  is inserted through the endoscope insertion passage  306 , as illustrated in  FIG. 6 , the endoscope insertion part  102  is inserted through the through-hole  432  of the pressure-contact member  426 . 
     In addition, the position of an outer peripheral surface of the pressure-contact member  426  in the opening  430  of the pressure-contact member attachment part  428  substantially coincides with the position of the left side surface  431  of the slider body  402  around the opening  430 . That is, the opening  430  of the pressure-contact member attachment part  428  provides a space for arranging the pressure-contact member  426 , and as compared to a configuration in which the pressure-contact member  426  is completely housed inside the slider body  402 , the slider body  402  is miniaturized, and the external diameter of the overtube body  320  is also made smaller along with this miniaturization. However, a configuration in which the pressure-contact member  426  is completely housed inside the slider body  402  may be adopted. 
     Additionally, the internal diameter (the diameter of the through-hole  432 ) of the pressure-contact member  426  is slightly smaller than the external diameter of the endoscope insertion part  102 . 
     Therefore, when the endoscope insertion part  102  is inserted through the through-hole  432  of the pressure-contact member  426 , the through-hole  432  is pushed and widened and the pressure-contact member  426  is deformed. An elastic force is generated in the pressure-contact member  426  due to this deformation, and the pressure-contact member  426  is brought into pressure contact (engaged) with the endoscope insertion part  102  inserted through the through-hole  432 . 
     Therefore, a frictional force acts on the relative movement between the endoscope insertion part  102  and the pressure-contact member  426 . Then, unless a larger external force than the frictional force is applied between the endoscope insertion part  102  and the pressure-contact member  426 , the relative movement does not occur between the endoscope insertion part  102  and the pressure-contact member  426 , and the endoscope insertion part  102  and the slider  400  (slider body  402 ) are brought into a state where they are coupled (engaged) in an interlockable manner via the pressure-contact member  426 . 
     Accordingly, the slider  400  (slider body  402 ) also integrally moves forward and backward in an interlocking manner with the forward and backward movement of the endoscope insertion part  102  in the forward-rearward direction (axial direction). 
     In addition, since the coupling here is based on the elastic force of the pressure-contact member  426 , the engagement position (a position where the slider  400  is engaged in the endoscope insertion part  102 ) of the endoscope insertion part  102  coupled to the slider  400  (slider body  402 ) can be arbitrarily adjusted. 
     (Description of Treatment Tool-Coupled Part) 
     The treatment tool-coupled part  422 , as illustrated in  FIG. 10  is provided on the right side of the slider body  402 , and includes a sleeve  440  (sleeve member) that is coupled to the treatment tool insertion part  202 , and a guide part  460  that guides the sleeve  440  so as to be movable forward and backward in the direction (forward-rearward direction) of the treatment tool insertion axis  308   a.    
     The sleeve  440  is housed in a sleeve housing space  464  of the guide part  460  to be described below in detail, is supported so as to be movable forward and backward in the forward-rearward direction, and as illustrated in  FIG. 7 , includes a sleeve body (frame body)  444  that surrounds the outside of the sleeve, and a pressure-contact member  446  that is arranged inside the sleeve. 
     The sleeve body  444  is formed in a cylindrical shape, and has a through-hole  448  with a larger diameter than the external diameter of at least the treatment tool insertion part  202 . The central axis of the through-hole  448  is arranged coaxially with the treatment tool insertion axis  308   a  within the lumen  324  of the overtube body  320 , and secures a space for the treatment tool insertion passage  308 . 
     The pressure-contact member  446  is annularly formed of an elastic material, such as elastic rubber or a spring, and is fitted into the through-hole  448  of the sleeve body  444  and fixed to the sleeve body  444 . A central axis of a through-hole  450  of the pressure-contact member  446  is arranged coaxially with the treatment tool insertion axis  308   a  within the lumen  324  of the overtube body  320 . 
     Therefore, when the treatment tool insertion part  202  is inserted through the treatment tool insertion passage  308 , as illustrated in  FIG. 6 , the treatment tool insertion part  202  is inserted through the through-hole  450  of the pressure-contact member  446 . 
     Additionally, the internal diameter (the diameter of the through-hole  450 ) of the pressure-contact member  446  is slightly smaller than the external diameter of the treatment tool insertion part  202 . 
     Therefore, when the treatment tool insertion part  202  is inserted through the through-hole  450  of the pressure-contact member  446 , the through-hole  450  is pushed and widened and the pressure-contact member  446  is deformed. An elastic force is generated in the pressure-contact member  446  due to this deformation, and the pressure-contact member  446  is brought into pressure contact (engaged) with the treatment tool insertion part  202  inserted through the through-hole  450 . 
     Therefore, a frictional force acts on the relative movement between the treatment tool insertion part  202  and the pressure-contact member  446 . Then, unless a larger external force than the frictional force is applied between the treatment tool insertion part  202  and the pressure-contact member  446 , the relative movement does not occur between the treatment tool insertion part  202  and the pressure-contact member  446 , and the treatment tool insertion part  202  and the sleeve  440  are brought into a state where they are coupled (engaged) in an interlockable manner via the pressure-contact member  446 . 
     Accordingly, the sleeve  440  also integrally moves forward and backward in an interlocking manner with the forward and backward movement of the treatment tool insertion part  202  in the forward-rearward direction (axial direction). 
     Additionally, the sleeve  440  also rotates with respect to the slider body  402  in an interlocking manner with the rotation around the axis of the treatment tool insertion part  202 . 
     In addition, since the coupling between the treatment tool insertion part  202  and the sleeve  440  herein is based on the elastic force of the pressure-contact member  446 , the engagement position (a position where the sleeve  440  is engaged in the treatment tool insertion part  202 ) of the treatment tool insertion part  202  coupled to the sleeve  440  can be arbitrarily adjusted. 
     Additionally, a region where the endoscope insertion part  102  is fixed to the endoscope-coupled part  420  of the slider  400  is referred to as an endoscope fixed region, and a region where the treatment tool insertion part  202  is fixed to the treatment tool-coupled part  422  of the slider  400  is referred to as a treatment tool fixed region. In the present form, the endoscope fixed region is equivalent to a region of an inner peripheral surface of the pressure-contact member  426  that is brought into pressure contact with the outer peripheral surface of the endoscope insertion part  102 , and the treatment tool fixed region is equivalent to a region of an inner peripheral surface of the pressure-contact member  446  that is brought into pressure contact with the outer peripheral surface of the treatment tool insertion part  202 . In this case, it is desirable that the endoscope fixed region is configured so as to become longer in the axial direction than the treatment tool fixed region. 
     Meanwhile, the guide part  460  of the treatment tool-coupled part  422 , as illustrated in  FIGS. 7 and 9 , has a guide surface  462  that extends in the direction of the treatment tool insertion axis  308   a  (reference axis  300   a ) within the lumen  324  of the overtube body  320 . 
     The guide surface  462  is curved in a U-shape toward an opening in a section orthogonal to the reference axis  300   a , and as illustrated in  FIG. 7 , an inner peripheral surface of the overtube body  320  (outer wall  322 ) is arranged so as to face the opening of the guide surface  462 , within the lumen  324  of the overtube body  320 . 
     Accordingly, a space surrounded by the guide surface  462  and the inner peripheral surface of the overtube body  320  is formed as the sleeve housing space  464  of the guide part  460 . 
     The sleeve housing space  464  is formed at a position where the treatment tool insertion axis  308   a  is inserted therethrough, and extends along the treatment tool insertion axis  308   a.    
     The sleeve  440  is housed and arranged in the sleeve housing space  464  as described above, and a central axis of the sleeve  440  is arranged coaxially with the treatment tool insertion axis  308   a.    
     In the sleeve housing space  464 , an outer peripheral surface of the sleeve  440  comes in contact with or approaches the guide surface  462  and the inner peripheral surface of the overtube body  320 . 
     Accordingly, in the sleeve housing space  464 , the sleeve  440  is supported so as to be movable in the forward-rearward direction and rotatable around the axis, and is supported in a state where the movement of the sleeve in the upward-downward direction and in the leftward-rightward direction is restricted. 
     Additionally, the guide part  460  (slider body  402 ), as illustrated in  FIGS. 9 and 10 , has end edge parts  466  and  468 , which are formed to protrude in a direction orthogonal to the guide surface  462  along an end edge of the guide surface  462 , respectively, on the base end side and the distal end side thereof. 
     The end edge parts  466  and  468  abut against the end part of the sleeve  440  to restrict the movement of the sleeve  440 , when the sleeve  440  arranged in the sleeve housing space  464  moves forward and backward in the forward-rearward direction. 
     Therefore, a range (movable range) where the sleeve  440  moves forward and backward in the forward-rearward direction with respect to the slider body  402  is limited with a position where the sleeve abuts against the end edge part  466  being defined as a rear end and a position where the sleeve abuts against the end edge part  468  being defined as a front end. However, the rear end and the front end of the movable range of the sleeve  440  may not be restricted by the end edge part  466  and the end edge part  468 . 
     In addition, in the present embodiment, the sleeve housing space  464  of the guide part  460  is formed by the guide surface  462  of the slider body  402  and the inner peripheral surface of the overtube body  320 . Therefore, as compared to a configuration in which the sleeve housing space  464  is formed only by the slider body  402  and the sleeve  440  is completely housed inside the slider body  402 , the slider body  402  is miniaturized, and the external diameter of the overtube body  320  is also made smaller along with this miniaturization. However, a configuration in which the sleeve  440  is completely housed inside the slider body  402  may not be adopted. 
     (Action of Slider when Endoscope and Treatment Tool are Coupled) 
     According to the slider  400  configured as described above, the endoscope insertion part  102  inserted through the endoscope insertion passage  306  of the overtube  300  and the slider body  402  are coupled, and the treatment tool insertion part  202  inserted through the treatment tool insertion passage  308  of the overtube  300  and the sleeve  440  are coupled. 
     As illustrated in  FIG. 11 , it is supposed that a surgeon performs a forward and backward movement for moving the treatment tool insertion part  202  forward and backward in the axial direction (forward-rearward direction) in a state where the sleeve  440  has not reached the rear end and the front end of the movable range thereof with respect to the slider body  402 . 
     In this case, when the sleeve  440  has moved forward and backward within the movable range thereof with respect to the slider body  402 , the slider body  402  does not move with respect to the forward and backward movement of the treatment tool insertion part  202 . Therefore, the dead zone where the endoscope insertion part  102  does not interlock with the forward and backward movement of the treatment tool insertion part  202  is present. 
     On the other hand, as illustrated in  FIG. 12 , if the treatment tool insertion part  202  is moved backward in a state where the sleeve  440  reaches the rear end of the movable range thereof with respect to the slider body  402 , the sleeve  440  and the slider body  402  move backward with respect to the overtube body  320  together with the treatment tool insertion part  202 . Accordingly, the endoscope insertion part  102  moves backward in an interlocking manner with the treatment tool insertion part  202 . 
     Similarly, as illustrated in  FIG. 13 , if the treatment tool insertion part  202  is moved forward in a state where the sleeve  440  reaches the front end of the movable range thereof with respect to the slider body  402 , the sleeve  440  and the slider body  402  move forward with respect to the overtube body  320  together with the treatment tool insertion part  202 . Accordingly, the endoscope insertion part  102  moves forward in an interlocking manner with the treatment tool insertion part  202 . 
     Therefore, when the treatment tool insertion part  202  has been largely displaced in the axial direction as described above (when the forward and backward movement of a large amplitude has been performed), the endoscope insertion part  102  is displaced in the axial direction in an interlocking manner with the treatment tool insertion part  202 , and when the displacement of the treatment tool insertion part  202  in the axial direction is small (when the forward and backward movement of a small amplitude is performed), the endoscope insertion part  102  is not displaced in the axial direction. 
     Additionally, in the present embodiment, the slider body  402  is restricted only in forward and backward movement in the forward-rearward direction, whereas the sleeve  440  is supported so as to be rotatable around the axis with respect to the slider body  402 . Therefore, as illustrated in  FIG. 14 , when the treatment tool insertion part  202  is operated to rotate around the axis, the slider body  402  does not rotate, and the treatment tool insertion part  202  and the sleeve  440  rotate around the axis. 
     Therefore, the rotational angle of the treatment tool insertion part  202  around the axis can be changed, without changing the positions of the endoscope insertion part  102  and the treatment tool insertion part  202  (the positions thereof within a body cavity) with respect to the overtube  300 . 
     That is, when a treatment is performed on a predetermined affected part by inserting the endoscope insertion part  102  and the treatment tool insertion part  202  through the overtube  300  inserted into a body wall, in a general procedure, the endoscope  100  is used such that the position of the endoscope insertion part  102  in the upward-downward direction and in the leftward-rightward direction and the rotational angle thereof around the axis are fixed. 
     Meanwhile, the rotational operation of the treatment tool insertion part  202  around the axis is appropriately performed similar to the forward and backward movement so that the treatment tool  200  is easily operated by a surgeon. 
     In the overtube  300  of the present embodiment, the endoscope insertion part  102  and the treatment tool insertion part  202  are coupled by the slider  400 . Thus, there is a concern that the positions of the endoscope insertion part  102  in the upward-downward direction and in the leftward-rightward direction and the rotational angle thereof around the axis may fluctuate due to the rotational operation or the like of the treatment tool insertion part  202 . 
     However, since operations other than the forward and backward movement of the slider  400  are restricted as described above, the treatment tool insertion part  202  can be rotated around the axis without changing the positions of the endoscope insertion part  102  in the upward-downward direction and in the leftward-rightward direction and the rotational angle thereof around the axis, and the degree of freedom (five degrees of freedom) required for the operation of forceps operation is obtained. In addition, the five degrees of freedom of the operation of the forceps are the movement of the forceps with respect to an internal organ, and indicate five movements of the forceps including the movements of the forceps in the longitudinal direction, the transverse direction, and the forward and backward movement direction, the rotation of the forceps, and the opening/closing operation of the forceps. 
     (Operating Conditions of Slider) 
     Next, the operating conditions of the slider  400  will be described. Here, forces that act on the respective members related to the operation of the slider  400  are defined as follows. 
     A force with which the pressure-contact member  426  of the endoscope-coupled part  420  fixes the endoscope insertion part  102  at a fixed position of the outer peripheral surface thereof is referred to as a fixing force for fixing the slider body  402  to the endoscope insertion part  102 , and the magnitude of the fixing force (the fixing force for fixing the endoscope insertion part  102  at the fixed position in the axial direction) with respect to the axial direction (forward-rearward direction) is defined as F1. 
     Similarly, a force with which the pressure-contact member  446  of the sleeve  440  in the treatment tool-coupled part  422  fixes the treatment tool insertion part  202  at a fixed position of the outer peripheral surface thereof is referred to as a fixing force for fixing the sleeve  440  to the treatment tool insertion part  202 , and the magnitude of the fixing force with respect to the axial direction (forward-rearward direction) is defined as F2. 
     Meanwhile, a frictional force received from the valve member  346  when the endoscope insertion part  102  moves forward and backward is defined as F3, and a frictional force received from the valve member  348  when the treatment tool insertion part  202  moves forward and backward is defined as F4. 
     Additionally, a frictional force received from a peripheral member when the sleeve  440  moves forward and backward with respect to the slider body  402  is defined as F5, and a frictional force received from the peripheral member when the slider body  402  moves forward and backward with respect to the overtube body  320  is defined as F6. 
     (a) Conditions in which Endoscope and Treatment Tool are Interlocked with Each Other when Forward and Backward Movement Width of Treatment Tool is Large 
     When the treatment tool insertion part  202  has been moved forward and backward (when the treatment tool insertion part has been markedly moved forward and backward), as conditions in which the endoscope insertion part  102  and the treatment tool insertion part  202  are integrally moved forward and backward via the slider  400 , the fixing forces F1 and F2, and the frictional force F3 satisfy the following conditions (1) and (2).
 
 F 1&gt; F 3  (1)
 
 F 2&gt; F 3  (2)
 
     Accordingly, if the sleeve  440  reaches the rear end or the front end of the movable range thereof with respect to the slider body  402  as illustrated in  FIG. 12 or 13  when the treatment tool insertion part  202  has been moved forward and backward, the sleeve  440  receives the frictional force F3 of the valve member  346  via the slider body  402  and the endoscope insertion part  102 . In this case, since the endoscope insertion part  102  and the slider body  402  are coupled by a larger fixing force F1 than the frictional force F3 and the treatment tool insertion part  202  and the sleeve  440  are coupled by a larger fixing force F2 than the frictional force F3, the slider body  402  moves forward and backward in an interlocking manner with the forward and backward movement of the treatment tool insertion part  202 , and the endoscope insertion part  102  moves forward and backward in an interlocking manner with the forward and backward movement of the slider body  402 . 
     Therefore, when the treatment tool insertion part  202  has been moved forward and backward, there is no case where, due to the frictional force of the valve member  346 , the engagement position of the endoscope insertion part  102  engaged with the slider body  402  shifts and the engagement position of the treatment tool insertion part  202  engaged with the sleeve  440  also shifts. 
     In addition, when the treatment tool insertion part  202  has been moved forward and backward, as a condition for moving the slider body  402  forward and backward with respect to the overtube body  320  in an interlocking manner with this operation, the fixing force F2 and the frictional force F6 satisfy the following condition (3).
 
 F 2&gt; F 6  (3)
 
     Similarly, when the endoscope insertion part  102  has been moved forward and backward, in order to move the endoscope insertion part  102  and the treatment tool insertion part  202  forward and backward integrally via the slider  400 , the fixing forces F1 and F2, and the frictional force F4 satisfy the following conditions (4) and (5).
 
 F 1&gt; F 4  (4)
 
 F 2&gt; F 4  (5)
 
     Additionally, when the endoscope insertion part  102  has been moved forward and backward, as a condition for moving the slider body  402  forward and backward with respect to the overtube body  320  in an interlocking manner with this operation, the fixing force F1 and the frictional force F6 satisfy the following condition (6).
 
 F 1&gt; F 6  (6)
 
     (b) Conditions in which Endoscope and Treatment Tool are not Interlocked with Each Other when Forward and Backward Movement Width of Treatment Tool is Small 
     When the treatment tool insertion part  202  has been moved forward and backward with a small width, as a condition for moving only the treatment tool insertion part  202  forward and backward without moving the endoscope insertion part  102  forward and backward as illustrated in  FIG. 11 , the frictional forces F3, F5, and F6 satisfy the following condition (7).
 
 F 3+ F 6&gt; F 5  (7)
 
     As a result, as illustrated in  FIG. 11 , when the movement width of the treatment tool insertion part  202  is small, the endoscope insertion part  102  does not move, and when the forward and backward movement width of the treatment tool insertion part  202  is large, the endoscope insertion part  102  moves. That is, when the forward and backward movement width of the treatment tool insertion part  202  is small, the sleeve  440  moves forward and backward only within the slider body  402 , and the slider body  402  itself does not move with respect to the overtube body  320 . Thus, the endoscope insertion part  102  does not move forward and backward in the axial direction (forward-rearward direction). 
     In addition, since F6 is considered to be substantially 0 when the frictional resistance of the slider body  402  with respect to the overtube body  320  is small enough to be ignored compared to the frictional force between the endoscope insertion part  102  and the valve member  346 , the condition (7) becomes F3&gt;F5. 
     On the other hand, when the forward and backward movement width of the treatment tool insertion part  202  is large, the sleeve  440  moves forward and backward within the slider body  402 , is struck against the distal end side or the base end side of the slider body  402  and moves the slider body  402  itself with respect to the overtube body  320 . Thus, the endoscope insertion part  102  coupled to the slider body  402  also moves forward and backward. 
     (c) Conditions for Adjustment of Length of Treatment Tool Insertion Part  202   
     As a condition for adjusting the length of the treatment tool insertion part  202  while gripping the endoscope  100  and the treatment tool  200 , it is preferable that the fixing force F1 and F2 satisfy the following condition (8).
 
 F 1&gt; F 2  (8)
 
     Accordingly, even when the treatment tool insertion part  202  has been moved forward and backward using the overtube body  320  or even when the treatment tool insertion part  202  has been moved forward and backward using the endoscope insertion part  102 , the engagement position of the treatment tool insertion part  202  using the slider body  402  can be changed without changing the engagement position of the endoscope insertion part  102  engaged with the slider body  402 . 
     When the length of the treatment tool insertion part  202  is adjusted by moving the treatment tool insertion part  202  forward and backward using the overtube body  320 , frictional forces are generated between the sleeve  440  and the treatment tool insertion part  202  and between the valve member  348  and the treatment tool insertion part  202 . Thus, the operating force required for the forward and backward movement of the treatment tool insertion part  202  is F2+F4. Therefore, in order to allow a surgeon to perform such an adjustment operation without feeling stress, it is desirable that the fixing force F2 and the frictional force F4 satisfy the following condition (9).
 
 F 2+ F 4&lt;10 N (N is Newtons)  (9)
 
     Meanwhile, when the length of the treatment tool insertion part  202  is adjusted by moving the treatment tool insertion part  202  forward and backward using the endoscope insertion part  102 , if f4&gt;f3 is satisfied, the same frictional forces as above are generated. Thus, it is desirable to satisfy Expression (9). If F3&lt;F4 is satisfied, frictional forces are generated between the sleeve  440  and the treatment tool insertion part  202  and between the valve member  346  and the endoscope insertion part  102 . Thus the operating force required for the forward and backward movement of the treatment tool insertion part  202  is F2+F3. Therefore, in order to allow a surgeon to perform such an adjustment operation without feeling stress, it is desirable that the fixing force F2 and the frictional force F3 satisfy the following condition (10).
 
 F 2 +F 3&lt;10 N (N is Newtons)  (10)
 
     The invention is effective not only when both of the condition (9) and the condition (10) are satisfied but also when only any one of these conditions is satisfied. 
     In addition, even when the fixing forces F1 and F2 satisfy the following Expression (11), the length of the treatment tool insertion part  202  can be adjusted. In this case, however, the engagement position between the endoscope insertion part  102  and the slider body  402  may move, and the positional adjustment between the slider body  402  and the endoscope insertion part  102  may be separately required.
 
 F 1 &lt;F 2  (11)
 
     In order to allow a surgeon to perform such an adjustment operation without feeling stress, it is desirable that the fixing force F1 and the frictional force F3 or F4 satisfy the following condition (12) or (13).
 
 F 1 +F 4&lt;10 N (N is Newtons)  (12)
 
 F 1 +F 3&lt;10 N (N is Newtons)  (13)
 
     (d) Conditions for Securing Excellent Operability 
     As a condition in which a surgeon can perform the forward and backward movement of the treatment tool insertion part  202  without feeling stress, it is preferable that the frictional forces F3, F4, and F6 satisfy the following condition (14).
 
 F 3 +F 4 +F 6&lt;10 N (N is Newtons)  (14)
 
     In this way, by setting the required operating force (F3+F4+F6) when a surgeon moves the treatment tool insertion part  202  forward and backward markedly, a surgeon can secure excellent operability without feeling stress. 
     (e) Conditions for Preventing Overtube from Shifting with Respect to Body Wall 
     As a condition in which the overtube  300  (overtube body  320 ) is prevented from shifting due to the forward and backward movement of the treatment tool insertion part  202 , if the fixing force of the overtube  300  in the forward-rearward direction (axial direction) with respect to a body wall is defined as Ft, the fixing force Ft and the frictional forces F3 and F4 satisfy the following condition (15).
 
 Ft&gt;F 3 +F 4  (15)
 
     Accordingly, even if the treatment tool insertion part  202  has been moved forward and backward, the overtube  300  (overtube body  320 ) inserted into a body wall is fixed in a stable state without shifting. Thus, it is possible to secure excellent operability. 
     (Other Forms of Slider) 
     In the above overtube  300 , a supporting mechanism of the slider  400  adapted to be capable of moving the slider  400  forward and backward only in the forward-rearward direction with respect to the overtube body  320  is not limited to the above form. 
       FIG. 15  is a sectional view illustrating another form of the overtube  300  by the section orthogonal to the reference axis  300   a . In addition, the same reference signs will be given to constituent elements of the same or similar actions as those of the above form, and the description thereof will be omitted. 
     In the form illustrated in this drawing, guide rods  470  and  472 , which are laid from the base end (base end cap  340 ) to the distal end (distal end cap  360 ), are arranged along the direction of the reference axis  300   a  at the upper part and the lower part within the lumen  324  of the overtube body  320 . 
     Meanwhile, guide holes  474  and  476 , which penetrate from the base end to the front end, are formed at the upper part and the lower part of the slider body  402  of the slider  400 . 
     The guide rods  470  and  472  are respectively inserted through the guide holes  474  and  476 , and the slider  400  is supported within the lumen  324 . 
     Accordingly, the slider  400  is supported so as to be movable forward and backward only in the forward-rearward direction with respect to the overtube body  320 . 
       FIG. 16  is a sectional view illustrating still another form of the overtube  300  by the section orthogonal to the reference axis  300   a . In addition, the same reference signs will be given to constituent elements of the same or similar actions as those of the above form, and the description thereof will be omitted. 
     As illustrated in this drawing, the inner peripheral surface of the overtube body  320  (outer wall  322 ), that is, the outer shape of the lumen  324 , is formed in an elliptical shape in the section orthogonal to the reference axis  300   a.    
     Meanwhile, the slider  400  is formed so that the outer peripheral surface of the slider body  402  that is a frame body has a shape along an ellipse of the same shape as the lumen  324  in the section orthogonal to the reference axis  300   a  and the outer peripheral surface of the slider body  402  contacts or approaches the inner peripheral surface of the overtube body  320 . 
     Accordingly, the slider  400  is supported so as to be movable forward and backward only in the forward-rearward direction with respect to the overtube body  320 . 
     In addition, the shape of the slider is not limited to this, and the shape of the inner peripheral surface of the overtube body  320  and the shape of the slider body  402  in the section orthogonal to the reference axis  300   a  only has to be a combination of non-rotatable shapes. For example, in the forms illustrated in  FIGS. 7 and 15 , if the shape of the inner peripheral surface of the overtube body  320  is formed in an elliptical shape as illustrated in  FIG. 16  and the inner peripheral surface of the overtube body  320  is circumscribed on the slider body  402 , similar to the form of  FIG. 16 , special guide means, such as the form of the protruding strips  408  and  410 , the guide plates  374  and  376  in the form of  FIG. 7  and the guide rods  470  and  472  and the guide holes  474  and  476  in the form of  FIG. 15 , can be made unnecessary. 
     (Conditions for Preventing Endoscope Insertion Part from Entering Overtube) 
     Next, the engagement position of the endoscope insertion part  102  engaged with the slider  400  will be described. 
     In addition, in the following, the engagement position of the endoscope insertion part  102  engaged with the slider  400  (slider body  402 ) is mainly referred to as a coupling position, and represents the position of the endoscope insertion part  102  to which the endoscope-coupled part  420 , illustrated in  FIG. 10  and the like, of the slider  400  is coupled. 
     The surgeon or the like can freely change the coupling position of the endoscope insertion part  102  with respect to the slider  400  as described above. 
     Therefore, for example, when the treatment tool insertion part  202  has been moved backward in a state where the endoscope insertion part  102  and the treatment tool insertion part  202  are respectively inserted through the endoscope insertion passage  306  and the treatment tool insertion passage  308  of the overtube  300 , there is a possibility that the distal end (distal end surface  114 ) of the endoscope insertion part  102  that has moved backward in an interlocking manner with the backward movement of the treatment tool insertion part  202  may enter the inside (a portion closer to the base end side than the endoscope delivery opening  312 ) of the overtube  300 . 
     If the distal end of the endoscope insertion part  102  enters the inside of the overtube  300 , the observation visual field of the endoscope  100  is blocked by the overtube  300 , and a malfunction such that treatment cannot be performed occurs. 
     Additionally, when the distal end of the endoscope insertion part  102  has been soiled, the work of inserting the endoscope insertion part  102  into the overtube  300  is performed after the endoscope insertion part  102  has first been extracted and cleaned from the overtube  300 . 
     In this case, in order to return the positional relationship in the axial direction between the distal end (treatment part  206 ) of the treatment tool insertion part  202  and the distal end of the endoscope insertion part  102  to an original state, it is necessary to set the coupling position of the endoscope insertion part  102  with respect to the slider  400  to an original position. 
     However, since the slider  400  is movable forward and backward with respect to the overtube body  320 , there is a problem in that the coupling position of the endoscope insertion part  102  with respect to the slider  400  cannot be precisely grasped and it is difficult to return the coupling position to the original position. 
     It is suitable to adopt the following form in order to solve these problems. 
       FIG. 17  is a sectional view of the overtube  300  illustrating a state where the slider body  402  has been arranged at the rear end of the movable range thereof with respect to the overtube body  320  in a state where the endoscope insertion part  102  and the treatment tool insertion part  202  have been inserted through the endoscope insertion passage  306  and the treatment tool insertion passage  308  of the overtube  300 . 
     First, the coupling position of the endoscope-coupled part  420  with respect to the slider  400  in the direction of the reference axis  300   a  is defined as the position (a position that faces a rear end  426   e ) of the rear end  426   e  of the pressure-contact member  426  of the slider  400 . 
     As illustrated in this drawing, the length from the coupling position of the endoscope insertion part  102  to the distal end (distal end surface  304 ) of the overtube  300  in a state where the slider body  402  is arranged at the rear end of the movable range thereof with respect to the overtube body  320  is defined as L. 
     In contrast, the coupling position of the endoscope insertion part  102  is set to a position where the length Ls from the coupling position to the distal end (distal end surface  114 ) of the endoscope insertion part  102  satisfies the following condition (16).
 
 Ls≥L   (16)
 
     Accordingly, even when the slider body  402  has moved to the rear end of the movable range as illustrated in  FIG. 17 , the slider body  402  is arranged at a position where the distal end of the endoscope insertion part  102  coincides with the distal end of the overtube  300  or a position where the distal end of the endoscope insertion part  102  protrudes further forward than the distal end of the overtube  300 . 
     Therefore, a situation where the distal end of the endoscope insertion part  102  enters the inside of the overtube  300  is prevented beforehand. 
     In addition, although the coupling position of the endoscope insertion part  102  with respect to the slider  400  has been set to the position of the rear end  426   e  of the pressure-contact member  426 , the above condition (16) is satisfied even in a case where positions other than the rear end  426   e  of the pressure-contact member  426  are defined as the coupling position. However, the length L hereinbelow indicates the length from the position of the rear end  426   e  of the pressure-contact member  426  to the distal end of the overtube  300 . 
     Additionally, by configuring the invention so that the coupling position of the endoscope insertion part  102  can be set to a specific position that satisfies the condition (16), even in a case where the endoscope insertion part  102  is inserted into the overtube  300  after the endoscope insertion part  102  has first been extracted from the overtube  300 , the coupling position of the endoscope insertion part  102  can be easily reset to the original position. 
     (Configuration Example for Preventing Endoscope Insertion Part from Entering Overtube) 
       FIG. 18  is a plan view illustrating an embodiment of the endoscope  100  that can prevent the distal end of the endoscope insertion part  102  from entering the overtube  300 . 
     As illustrated in this drawing, the endoscope insertion part  102  of the endoscope  100  has a stepped part  154  at a predetermined position, a smaller-diameter part  150  located closer to the distal end side than the stepped part  154 , and a larger-diameter part  152  located closer to the base end side than the stepped part  154 . 
     The smaller-diameter part  150  has a diameter of a size such that the smaller-diameter part is insertable through the endoscope insertion passage  306  of the overtube  300  but the slider  400  (endoscope-coupled part  420 ) is not coupled thereto. That is, the smaller-diameter part  150  is smaller than the internal diameter of the pressure-contact member  426  (refer to  FIG. 6  and the like) that is an endoscope engagement part of the slider  400 , and is not engageable with the pressure-contact member  426 . 
     Additionally, the smaller-diameter part  150  has a length L0 greater than the above length L (L0≥L). 
     The larger-diameter part  152  is larger than the smaller-diameter part  150 , and has a diameter of a size such that the larger-diameter part is insertable through the endoscope insertion passage  306  of the overtube  300  and is brought into pressure contact with the pressure-contact member  426  of the slider  400  and the slider  400  (endoscope-coupled part  420 ) is coupled thereto. That is, the larger-diameter part  152  is slightly larger than the internal diameter of the pressure-contact member  426 , and is engageable with the pressure-contact member  426 , which is a frictional engagement part, through frictional engagement. 
     The stepped part  154  is formed at a boundary position between the smaller-diameter part  150  and the larger-diameter part  152 , and has a coupling surface that is an annular surface orthogonal to the axial direction and couples an outer peripheral surface of the smaller-diameter part  150  and an outer peripheral surface of the larger-diameter part  152 . 
       FIG. 19  is a sectional view illustrating a portion of the overtube  300  immediately after the slider  400  has been coupled to the endoscope insertion part  102  of  FIG. 18  in an enlarged manner. 
     When the endoscope insertion part  102  is inserted into and moved forward to the endoscope insertion passage  306  of the overtube  300  and the endoscope insertion part  102  is coupled to the slider  400 , as illustrated in this drawing, the smaller-diameter part  150  of the endoscope insertion part  102  passes through the through-hole  432  of the pressure-contact member  426 , without being brought into pressure contact with the pressure-contact member  426  of the slider  400 . 
     Then, if the stepped part  154  reaches the position of the rear end  426   e  of the pressure-contact member  426 , the pressure-contact member is pushed by the stepped part  154 , and the slider  400  moves forward together with the endoscope insertion part  102  and moves to the front end of the movable range thereof with respect to the overtube body  320 . 
     In addition, the treatment tool insertion part  202  is released without being gripped. 
     Thereafter, if the endoscope insertion part  102  is further moved forward, as illustrated in this drawing, the larger-diameter part  152  enters the through-hole  432  of the pressure-contact member  426 . 
     Accordingly, the larger-diameter part  152  is brought into pressure contact with the pressure-contact member  426  and is engaged with the pressure-contact member  426 , and the slider  400  is coupled to the endoscope insertion part  102 . 
     In this case, an operator who is performing a forward movement of the endoscope insertion part  102  can detect that the slider  400  has been coupled to the endoscope insertion part  102  because the operating force of the forward movement becomes large. Then, by further moving the endoscope insertion part  102  forward after it is detected that the slider  400  has been coupled to the endoscope insertion part  102 , the coupling position of the endoscope insertion part  102  with respect to the slider  400  can be adjusted. 
     In this way, when the endoscope insertion part  102  of  FIG. 18  is inserted into the endoscope insertion passage  306  of the overtube  300  and the endoscope insertion part  102  is coupled to the slider  400 , a state where the stepped part  154  of the endoscope insertion part  102  has been arranged closer to the front side than the rear end  426   e  of the pressure-contact member  426  of the slider  400  is achieved. 
     Therefore, the length from the position of the rear end  426   e  of the pressure-contact member  426  to the distal end of the endoscope insertion part  102 , that is, the length Ls from the coupling position of the endoscope insertion part  102  illustrated in  FIG. 17  to the distal end of the endoscope insertion part  102  becomes equal to or larger than the length L0 of the smaller-diameter part  150  of the endoscope insertion part  102  (Ls≥L0). 
     As described above, since the length L0 of the smaller-diameter part  150  becomes equal to or larger than the above length L (L0≥L), a state where the above condition (16) is satisfied in a state where the slider  400  has been coupled to the endoscope insertion part  102  is set. 
     Additionally, if the forward movement of the endoscope insertion part  102  is stopped when the operating force of the forward movement of the endoscope insertion part  102  becomes large as described above, and when it is detected that the slider  400  has been coupled to the endoscope insertion part  102 , as illustrated in  FIG. 19 , the coupling position (the position of the rear end  426   e  of the pressure-contact member  426 ) of the endoscope insertion part  102  with respect to the slider  400  substantially coincides with the position of the stepped part  154 . 
     That is, the operator can always set the coupling position of the endoscope insertion part  102  with respect to the slider  400  to the vicinity position of the stepped part  154  according to the operational feeling of the forward and backward movement of the endoscope insertion part  102 . 
     Therefore, if the endoscope insertion part  102  is used after being coupled to the slider  400  at the vicinity position of the stepped part  154 , even in a case where the endoscope insertion part  102  has first been extracted from the overtube  300 , the coupling position of the endoscope insertion part  102  with respect to the slider  400  can be easily reset to the original position when the endoscope insertion part  102  is inserted into the overtube  300 . 
     As described above, in the endoscope  100  of the above form, the endoscope insertion part  102  is adapted to be capable of being coupled to the slider  400  only at the position of the larger-diameter part  152  located closer to the base end side than the stepped part  154  of the endoscope insertion part  102 . However, the invention is not limited to this. 
     (Another Configuration Example for Preventing Endoscope Insertion Part from Entering Overtube) 
       FIG. 20  is a plan view illustrating another embodiment of the endoscope  100  that can prevent the distal end of the endoscope insertion part  102  from entering the overtube  300 . 
     The endoscope insertion part  102  of the endoscope  100  illustrated in this drawing has a diameter of a size that is constant in its entirety, and has a diameter of a size such that the endoscope insertion part is insertable therethrough the endoscope insertion passage  306  of the overtube  300  and is brought into pressure contact with the pressure-contact member  426  of the slider  400  and the slider  400  is coupled thereto. That is, the endoscope insertion part is slightly larger than the internal diameter of the pressure-contact member  426 . 
     Meanwhile, a high-friction part  170  (high friction member) having a higher frictional coefficient than the other portions is provided in an axial partial range of the endoscope insertion part  102 . 
     The high-friction part  170  is provided at a position where the length L1 from the position of a front end thereof to the distal end of the endoscope insertion part  102  becomes equal to or larger than the above length L (L1≥L). 
     According to this endoscope  100 , if the front end of the high-friction part  170  reaches the position of the rear end  426   e  of the pressure-contact member  426  when the endoscope insertion part  102  is inserted into and moved forward to the endoscope insertion passage  306  of the overtube  300  and is coupled to the slider  400 , the high-friction part  170  then enters the through-hole  432  of the pressure-contact member  426 . Accordingly, the operator who is performing the forward movement of the endoscope insertion part  102  can detect that the coupling position of the endoscope insertion part  102  with respect to the slider  400  has reached the high-friction part  170  because the operating force of the forward movement becomes large. 
     In this case, the length from the position of the rear end  426   e  of the pressure-contact member  426  to the distal end of the endoscope insertion part  102 , that is, the length Ls from the coupling position of the endoscope insertion part  102  illustrated in  FIG. 17  to the distal end thereof becomes equal to or larger than the above length L1 (Ls≥L1). As a result, a state where the above condition (16) is satisfied is set because the length L1 is equal to or larger than the above length L (L1≥L). 
     Therefore, if the slider  400  is coupled at a position where the endoscope insertion part  102  has been further moved forward with respect to the slider  400  after it is detected that the coupling position of the endoscope insertion part  102  has reached the high-friction part  170 , a state where the above condition (16) is satisfied can be set. 
     Meanwhile, if the slider  400  is coupled at the position where it is detected that the coupling position of the endoscope insertion part  102  has reached the high-friction part  170 , even in a case where the endoscope insertion part  102  has first been extracted from the endoscope insertion passage  306  of the overtube  300 , the coupling position of the endoscope insertion part  102  can be easily reset to the original position. 
     In the above form, the distal end of the endoscope insertion part  102  is adapted so as not to be arranged closer to the base end side than the distal end of the overtube  300  in a state where the slider  400  has been arranged at the rear end of the movable range thereof with respect to the overtube body  320 . However, the invention is not limited to this, and the distal end of the endoscope insertion part  102  can be adapted so as not to be arranged closer to the base end side than a reference position, using an arbitrary position other than the distal end of the overtube  300  as the reference position. 
     (Application to Treatment Tool Insertion Part) 
     Additionally, the treatment tool insertion part  202  can also be applied similar to the above embodiment regarding the endoscope insertion part  102 . That is, the same component parts as the stepped part  154  and the high-friction part  170  of the endoscope insertion part  102  illustrated in  FIG. 18  or  FIG. 20  may be provided in the treatment tool insertion part  202  so that the distal end of the treatment tool insertion part  202  engaged with the sleeve  440  is not located closer to the base end side than at least the distal end surface  304  of the overtube  300  or a desired reference position, in a state where the slider  400  is arranged at the rear end of the movable range thereof with respect to the overtube body  320  and the sleeve  440  is arranged at the rear end of the movable range thereof with respect to the slider body  402 . 
     (Description of Inner Needle) 
     Next, an inner needle  500  to be used after being mounted on the overtube  300  when the overtube  300  is inserted into a body wall will be described. 
       FIGS. 21 and 22  are respectively perspective views illustrating a state where the inner needle  500  has been mounted on the overtube  300  from the front upper left and from the rear lower left, and  FIG. 23  is a perspective view illustrating only the inner needle  500  from the front lower left. In addition, the relationship of front and rear, left and right, and up and down of the inner needle  500  follows the relationship of front and rear, left and right, and up and down of the overtube  300  when being mounted on the overtube  300  as illustrated in  FIG. 21 . 
     As illustrated in these drawings, the inner needle  500  is constituted of two rod parts  502  and  504  that are formed in an elongated shape, distal end parts  506  and  508  that are respectively formed at the distal ends of the rod parts  502  and  504 , and a head part  510  that is provided on the base end sides of the rod parts  502  and  504 . 
     The rod part  502  (first rod part) has a diameter equal to or smaller than the external diameter of the above-described endoscope insertion part  102 , and is formed with a size such that the rod part is insertable through the endoscope insertion passage  306 . As illustrated in  FIGS. 21 and 22 , when the inner needle  500  is mounted on the overtube  300 , the rod part  502  is arranged so as to be inserted through the endoscope insertion passage  306  of the overtube  300 . 
     Additionally, the rod part  502  is formed to be slightly longer than the length of the overtube  300  (endoscope insertion passage  306 ) in the forward-rearward direction, and when the inner needle  500  has been mounted on the overtube  300 , the distal end part  506  of the rod part  502  protrudes by a predetermined length from the endoscope delivery opening  312 . 
     The rod part  504  (second rod part) has a diameter equal to or smaller than the external diameter of the above-described treatment tool insertion part  202 , and is formed with a size such that the rod part is insertable through the treatment tool insertion passage  308 . As illustrated in  FIGS. 21 and 22 , when the inner needle  500  has been mounted on the overtube  300 , the rod part  504  is arranged so as to be inserted through the treatment tool insertion passage  308  of the overtube  300 . 
     Additionally, the shaft part  504  is formed to be slightly longer than the length of the overtube  300  (treatment tool insertion passage  308 ) in the forward-rearward direction, and when the inner needle  500  has been mounted on the overtube  300 , the distal end part  508  of the shaft part  504  protrudes by a predetermined length from the treatment tool delivery opening  316 . 
     Although the distal end parts  506  and  508  are formed in a curved surface shape and are configured to be dull so that no edge is formed (that is, in a rounded non-edge shape), the distal end parts are adapted to be capable of penetrating a body wall easily. 
     The head part  510  has a head part body  512  and a locking lever  514 . 
     The head part body  512 , as illustrated in  FIGS. 22 and 23 , has a shape surrounded by a side surface  522  along a column surface having an axis  520  extending in the forward-rearward direction in parallel with the rod parts  502  and  504  as a center having a diameter that approximately coincides with the external diameter of the base end cap  340  of the overtube  300 , a lower surface  524  along a plane which is parallel to the axis  520  (parallel to the forward-rearward direction and the leftward-rightward direction) and which intersects the column surface along which the side surface  522  runs, and a rear end surface  526  and a front end surface  528  along a plane orthogonal to the axis  520 . 
     In addition, the axis  520  is arranged coaxially with the reference axis  300   a  (not illustrated) of the overtube  300  in a state where the inner needle  500  has been mounted on the overtube  300 . 
     The front end surface  528  of the head part body  512  has the base end sides of the rod parts  502  and  504  fixed thereto, and the side surface  522  of the head part body  512  has the locking lever  514  provided along the direction (forward-rearward direction) of the axis  520  at a central part (topmost part) thereof in the circumferential direction. 
     The locking lever  514  is a constituent element of a fixing mechanism that detachably fixes the head part  510  of the inner needle  500  to the overtube  300 , is formed in an elongated plate shape extending along the direction of the axis  520 , and is supported by the head part body  512  so as to be turnable in such an orientation that a front end part and a rear end part are opposite to each other in the upward-downward direction with the vicinity of the center in the direction of the axis  520  as a fulcrum. 
     A locking claw  532  (refer to  FIG. 23 ) is provided to protrude from a lower surface side of a distal end part of the locking lever  514 , and the locking claw  532 , as illustrated in  FIGS. 3 and 5 , has such a shape that the locking claw is fitted to a locking hole  534  provided in the base end cap  340 . 
     Additionally, a biasing member, such as a coil spring, is arranged at the head part body  512  at a position on a lower surface side of a base end part of the locking lever  514 , and the locking lever  514  is biased so that the rear end part faces up and the front end part faces down. 
     (Action when Inner Needle is Mounted) 
     According to the inner needle  500  configured as above, if the rod parts  502  and  504  of the inner needle  500  are respectively inserted into the endoscope insertion passage  306  and the treatment tool insertion passage  308  from the endoscope insertion opening  310  and the treatment tool insertion opening  314 , respectively, of the overtube  300 , as illustrated in  FIG. 24 , the head part  510  of the inner needle  500  approaches the base end cap  340  of the overtube  300 . 
     Then, if the inner needle  500  is further inserted, as illustrated in  FIGS. 21 and 22 , the front end surface  528  of the head part body  512  abuts against the base end surface  302  of the overtube  300  (base end cap  340 ), and the locking claw  532  of the locking lever  514  is fitted to the locking hole  534  of the base end cap  340  and is brought into a state where the inner needle  500  has been mounted on (fixed to) the overtube  300 . 
     In this case, the distal end parts  506  and  508  of the rod parts  502  and  504  of the inner needle  500  are arranged so as to protrude by a predetermined length from the distal end of the overtube  300 . 
     Meanwhile, if the base end part of the locking lever  514  is pressed in a state where the inner needle  500  has been mounted on the overtube  300 , the locking claw  532  can be removed from the locking hole  534  of the base end cap  340 , and if the inner needle  500  is pulled out to the hand side in that state, the inner needle  500  can be detached from the overtube  300 . 
     Additionally, as described above, the head part body  512  of the inner needle  500  has such a shape that a lower side of a columnar member is cut out by the lower surface  524 . That is, the head part body  512  is provided with a cutout part formed by cutting out a portion that interferes with the air supply connector  318  when the inner needle  500  has been mounted on the overtube  300 . 
     Accordingly, the front end surface  528  of the head part body  512  can be made to abut against the base end surface  302  without interfering with the air supply connector  318  provided to protrude from the base end surface  302  of the overtube  300  (base end cap  340 ) as illustrated in  FIG. 22  when the inner needle  500  has been mounted on the overtube  300 , and the inner needle  500  can be mounted on the overtube  300  in a stable state. 
     In addition, the invention is not limited to the above form, and the head part body  512  only has to have the cutout part formed by cutting out the portion of the head part body  512  that interferes with at least the air supply connector  318  when the inner needle  500  has been mounted on the overtube  300 . Additionally, since the rotation of the head part body  512  is restricted with respect to the overtube  300  by the rod parts  502  and  504 , the head part body does not interfere with the air supply connector  318 . 
     &lt;Operation Method of Endoscopic Surgical Device&gt; 
     Next, an example of operation methods using the endoscopic surgical device  10  of the present embodiment will be described. 
       FIGS. 25A to 29B  are explanatory views illustrating a situation in which the endoscopic surgical device  10  of the present embodiment is operated. 
       FIGS. 25A to 25C  are views illustrating a situation in which the overtube  300  is inserted into a body wall. 
       FIGS. 26A to 27B  are views illustrating a situation in which the treatment tool insertion part  202  is pushed into an affected part side within a body cavity from the hand side. 
       FIGS. 28A to 29B  are views illustrating a situation in which the treatment tool insertion part  202  is pulled to the hand side from the affected part side within the body cavity. 
     First, as a preparation process for starting the operation of the endoscopic surgical device  10 , the overtube  300  is inserted into a skin incision part (incised wound) formed in a body wall in a state where the inner needle  500  is inserted into the overtube  300 , and the overtube  300  is inserted into the body cavity like a state designated by reference sign  1000  of part  FIG. 25A . 
     Next, the inner needle  500  is extracted from the endoscope insertion passage  306  and the treatment tool insertion passage  308  (the inner needle  500  is removed from the overtube  300 ), and one end part of the air supply tube  122  is connected to the air supply connector  318  of the overtube  300  like a state designated by reference sign  1002  of  FIG. 25B . The other end part is connected to the pneumoperitoneum device  120 . Then, pneumoperitoneum gas is delivered from the pneumoperitoneum device  120 , and the pneumoperitoneum gas is injected into the body cavity through the air supply tube  122  and the overtube  300 . 
     Next, the endoscope insertion part  102  is inserted into the endoscope insertion passage  306  from the endoscope insertion opening  310  of the overtube  300 , and the distal end of the endoscope insertion part  102  is led out from the endoscope delivery opening  312 . 
     In this case, the endoscope insertion part  102  has the endoscope-coupled part  420  of the slider  400  inserted therethrough, and is coupled to the slider body  402  as described above. Accordingly, the endoscope insertion part  102  and the slider  400  are brought into a state where they move integrally. 
     Subsequently, the treatment tool insertion part  202  is inserted into the treatment tool insertion passage  308  from the treatment tool insertion opening  314  of the overtube  300 , and the distal end (treatment part  206 ) of the treatment tool insertion part  202  is led out from the treatment tool delivery opening  316 . 
     In this case, the treatment tool insertion part  202  has the sleeve  440  of the treatment tool-coupled part  422  of the slider  400  inserted therethrough, and is coupled to the sleeve  440  as described above. Accordingly, the treatment tool insertion part  202  and the sleeve  440  are brought into a state where they move integrally. 
     If the preparation step is performed in this way, a state where the operation of the endoscopic surgical device  10  is operable is brought about like a state designated by reference sign  1004  of  FIG. 25C . 
     In addition, the distal end position of the endoscope insertion part  102  is arranged behind at least the distal end position of the treatment tool insertion part  202  so that the situation of the treatment part  206  at the distal end of the treatment tool insertion part  202  can be observed by the endoscope  100 . Additionally, the procedure of inserting the endoscope insertion part  102  and the treatment tool insertion part  202  into the overtube  300  is not limited to the above-described order, and the endoscope insertion part  102  may be inserted after the treatment tool insertion part  202  is inserted. 
     Next, a case where the treatment tool insertion part  202  is pushed into the affected part side within the body cavity from the hand side (a case where the treatment tool insertion part moves forward) will be described with reference to  FIGS. 26A to 27B . 
     First, when the treatment tool insertion part  202  has been minutely displaced in the axial direction like a state designated by reference sign  1008  of  FIG. 26B  from a state designated by reference sign  1006  of  FIG. 26A  (when a forward and backward movement of a small amplitude has been performed), only the treatment tool insertion part  202  moves forward and backward, and the slider  400  does not move forward and backward. Therefore, since the endoscope insertion part  102  does not move forward and backward, the range of an observation image displayed on the monitor  112  does not change. For this reason, the size of an object to be observed can be prevented from fluctuating according to the minute displacement of the treatment tool insertion part  202 , a sense of perspective can be suitably maintained, and a stable observation image can be obtained. 
     In contrast, when the treatment tool insertion part  202  has been largely displaced in the axial direction like a state designated by reference sign  1006  of  FIG. 27B  from a state designated by reference sign  1006  of  FIG. 27A  that is the same state as reference sign  1010  of  FIG. 26A  (when a forward and backward movement of a large amplitude has been performed), the slider  400  moves forward and backward in an interlocking manner with the forward and backward movement of the treatment tool insertion part  202 . In this case, since the endoscope insertion part  102  moves forward and backward, the range of an observation image displayed on the monitor  112  is continuously changed so as to follow the forward and backward movement of the treatment tool insertion part  202 . Accordingly, since the size of an object to be observed changes according to the operation of the treatment tool  200 , it is possible to simply obtain an image desired by a surgeon. 
     Additionally, the same applies to a case where the treatment tool insertion part  202  is pulled to the hand side from the affected part side within the body cavity (when the treatment tool insertion part moves backward) 
     That is, when the treatment tool insertion part  202  has been minutely displaced in the axial direction like a state designated by reference sign  1014  of  FIG. 28B  from a state designated by reference sign  1012  of  FIG. 28A  (when a forward and backward movement of a small amplitude has been performed), only the treatment tool insertion part  202  moves forward and backward, and the slider  400  does not move forward and backward. Therefore, since the endoscope insertion part  102  does not move forward and backward, the range of an observation image displayed on the monitor  112  does not change. For this reason, the size of an object to be observed can be prevented from fluctuating according to the minute displacement of the treatment tool insertion part  202 , a sense of perspective can be suitably maintained, and a stable observation image can be obtained. 
     In contrast, when the treatment tool insertion part  202  has been largely displaced in the axial direction like a state designated by reference sign  1016  of  FIG. 29B  from a state designated by reference sign  1012  of  FIG. 29A  that is the same state as reference sign  1012  of  FIG. 28A  (when a forward and backward movement of a large amplitude has been performed), the slider  400  moves forward and backward in an interlocking manner with the forward and backward movement of the treatment tool insertion part  202 . In this case, since the endoscope insertion part  102  moves forward and backward, the range of an observation image displayed on the monitor  112  is continuously changed so as to follow the forward and backward movement of the treatment tool insertion part  202 . Accordingly, since the size of an object to be observed changes according to the operation of the treatment tool  200 , it is possible to simply obtain an image desired by a surgeon. 
     &lt;Endoscopic Surgery&gt; 
     Next, an example of endoscopic surgery using the endoscopic surgical device  10  of the present embodiment will be described. 
     (Laparoscopic Gallbladder Removal Surgery) 
     Next, laparoscopic gallbladder removal surgery will be described as a first example of the endoscopic surgery. 
       FIG. 30  is a view illustrating a port arrangement (port design) in the laparoscopic gallbladder removal surgery. 
     In the laparoscopic gallbladder removal surgery using the endoscopic surgical device  10  of the present embodiment, as illustrated in  FIG. 30 , holes (ports) for allowing the endoscope and the treatment tool to be inserted into the abdominal cavity therethrough are formed in three places in the patient&#39;s abdomen. That is, in the present embodiment, the endoscope (equivalent to the above endoscope  100 ) and the treatment tool (equivalent to the above treatment tool  200 ) are inserted into the body cavity via the overtube (the first trocar equivalent to the above overtube  300 ) from the same port. Therefore, the number of ports is smaller by one compared to related-art multi-port (multi-hole type) laparoscopic gallbladder removal surgery. 
       FIG. 31  is a view illustrating a procedure of the laparoscopic gallbladder removal surgery. Additionally,  FIG. 32  is a view illustrating a procedure of a gallbladder treatment step. Hereinafter, the procedure of the laparoscopic gallbladder removal surgery will be described, referring to  FIGS. 31 and 32 . 
     [First Trocar Insertion Step] 
     First, after predetermined prior preparation has been performed (Step S 10 ) a first trocar insertion step is performed (Step S 12 ). In the first trocar insertion step, after a surgeon has incised a patient&#39;s abdominal wall surface, the surgeon and an assistant dilate the skin-incised part up to the peritoneum. Thereafter, the surgeon and the assistant integrally insert the first trocar into the skin-incised part. In addition, when the first trocar is inserted into an abdominal cavity, this insertion is performed in a state where an inner needle (equivalent to the above inner needle  500 ) is inserted through the inside of the first trocar. Then, after the insertion of the first trocar, the inner needle is extracted from the first trocar. Accordingly, at the time of the insertion of the first trocar, the tissue of an abdominal wall can be prevented from invading the inside of the first trocar. Additionally, when the first trocar inserted into the patient&#39;s abdominal cavity is likely to move, the surgeon and the assistant fix the first trocar to the abdominal wall with thread if necessary. 
     [Pneumoperitoneum Step] 
     Next, a pneumoperitoneum step is performed (Step S 14 ). In a pneumoperitoneum step, first, a pneumoperitoneum tube (equivalent to the above air supply tube  122 ) is connected to the first trocar. Next, a pneumoperitoneum device (equivalent to the above pneumoperitoneum device  120 ) is mounted on the pneumoperitoneum tube, and the pneumoperitoneum device is operated. Accordingly, pneumoperitoneum gas is supplied into the patient&#39;s abdominal cavity via the pneumoperitoneum tube and the first trocar from the pneumoperitoneum device. In this case, it is preferable that the air supply pressure of the pneumoperitoneum gas supplied into the patient&#39;s abdominal cavity is adjusted to a range of 8 mmHg to 12 mmHg (mmHg is about 133.322 Pa). In addition, the pneumoperitoneum step is not limited to the present example. For example, a pneumoperitoneum needle (not illustrated) may puncture a patient&#39;s abdominal wall in advance, and pneumoperitoneum gas may be supplied for pneumoperitoneum. 
     Additionally, in the pneumoperitoneum step, when the supplied gas supplied into the patient&#39;s abdominal cavity begins to leak to the outside, the surgeon ligates and sutures the pneumoperitoneum gas leakage part. 
     [Endoscope Insertion Step] 
     Next, an endoscope insertion step is performed (Step S 16 ). In the endoscope insertion step, the surgeon inserts an endoscope (equivalent to the above endoscope  100 ) into the first trocar while adjusting the fixed position of the endoscope insertion part to the slider (equivalent to the above slider  400 ) arranged inside the first trocar. In this case, it is preferable that the fixed position of the endoscope insertion part (equivalent to the above endoscope insertion part  102 ) with respect to the slider is adjusted so that a distal end part thereof protrudes from the first trocar by a predetermined length. Accordingly, the endoscope insertion part is inserted into the patient&#39;s abdominal cavity via the first trocar. 
     [Second Trocar Insertion Step] 
     Next, a Second Trocar Insertion Step is Performed (Step S 18 ). In the Second Trocar insertion process, the surgeon incises the patient&#39;s abdominal wall surface by about 7 mm to 8 mm and obtusely inserts the second trocar into the incised part (5 mm trocar) while checking an observation image (endoscope image) obtained by the endoscope inserted into the patient&#39;s abdominal cavity via the first trocar in the endoscope insertion process. Specifically, first, the surgeon directs the endoscope to another trocar breakthrough position, and projects an image of the peritoneum on a monitor. Next, the surgeon sends a finger sign of the abdominal wall while viewing the image, and checks the trocar breakthrough position. Thereafter, the surgeon incises the abdominal wall surface corresponding to the checked trocar breakthrough position by about 7 mm to 8 mm. After the incision, the surgeon obtusely inserts the second trocar into the incised part. In this case, the surgeon breaks through the abdominal wall while observing the endoscope image. Accordingly, the second trocar is safely inserted into the patient&#39;s abdominal cavity. 
     [Third Trocar Insertion Step] 
     Next, a third trocar insertion step is performed (Step S 20 ). The third trocar insertion step is performed similar to the second trocar insertion step. Accordingly, the third trocar is safely inserted into the patient&#39;s abdominal cavity. 
     [Observation Step] 
     Next, an observation step is performed (Step S 22 ). In the observation step, main parts are observed after the entire observation is performed. That is, the surgeon moves the endoscope backward to the hand side (rear side), observes the inside of the entire abdominal cavity with the endoscope, and performs checking of dissection and checking of an adhesion situation. Subsequently, the surgeon moves the endoscope forward to an affected part side (front side), and observes the vicinity of the gallbladder and the liver with the endoscope. 
     [Treatment Tool Insertion Step] 
     Next, a treatment tool insertion step is performed (Step S 24 ). In the treatment tool insertion step, the surgeon or the assistant sequentially inserts predetermined treatment tools into the patient&#39;s abdominal cavity via the first to third trocars, respectively. 
     Specifically, first, the surgeon inserts gripping forceps (5 mm gripping forceps) into the second trocar as a treatment tool. The treatment tool inserted into the second trocar is operated by a surgeon&#39;s left hand, and is hereinafter referred to as a surgeon left treatment tool. 
     Subsequently, the surgeon inserts gripping forceps (5 mm gripping forceps) into the first trocar as a treatment tool. The treatment tool (equivalent to the above treatment tool  200 ) inserted into the first trocar is operated by a surgeon&#39;s right hand, and is hereinafter referred to as a surgeon right treatment tool. If the surgeon right treatment tool is moved forward and backward with the surgeon&#39;s right hand in a state where the surgeon right treatment tool is inserted into the first trocar by an interlocking mechanism (equivalent to the above slider  400 ) of the above-described first trocar, the endoscope moves forward and backward with a predetermined amount of play together with the surgeon right treatment tool in an interlocking manner with this operation. Accordingly, the endoscope always picks up an image of forceps distal ends that enter the first trocar. Therefore, it is possible to operate the surgeon right treatment tool, thereby operating the endoscope simultaneously. 
     Subsequently, the assistant inserts the gripping forceps (5 mm gripping forceps) into the third trocar as the treatment tool. The treatment tool inserted into the third trocar is operated by an assistant&#39;s left (right) hand, and is hereinafter referred to as an assistant left treatment tool. 
     In addition, in the following steps, the treatment tools inserted into the first to third trocars, respectively, are replaced with other treatment tools if necessary, although not particularly clearly described. 
     [Gallbladder Treatment Step] 
     Next, a gallbladder treatment step is performed (Step S 26 ). In the gallbladder treatment step, the surgeon peels and removes the gallbladder from the inside of the patient&#39;s abdominal cavity. Specifically, the kidney treatment step is performed according to a procedure illustrated in  FIG. 32 . 
     That is, as illustrated in  FIG. 32 , first, a gallbladder exposure step is performed (Step S 50 ). In the gallbladder exposure step, when the surgeon holds and pulls the neck of the gallbladder with the surgeon left treatment tool (gripping forceps) and the surgeon right treatment tool (gripping forceps), the gallbladder is exposed. In addition, specifically, the gallbladder exposure step is performed according to the following procedure. 
     (1) The surgeon operates the surgeon right treatment tool and picks up an image of the entire liver. 
     (2) The surgeon raises the gallbladder with a belly part of the surgeon left treatment tool (grips and raises the gallbladder if it can be gripped). 
     (3) The surgeon grips and lifts the neck of the gallbladder with the surgeon right treatment tool. 
     (4) The surgeon re-grips the bottom of the gallbladder and the neck of the gallbladder with the surgeon left treatment tool. 
     (5) The surgeon moves the surgeon right treatment tool backward to the hand side (rear side), and observes the inside of the entire abdominal cavity with the endoscope. 
     In addition, in the present embodiment, the observation range (image pick-up range) of the endoscope may become smaller than that of the multi-port laparoscopic surgery. When it is desired to see an entire image in that case, the internal organs may be switched from one hand to the other hand again. Meanwhile, if the surgeon moves a treatment tool forward and backward, the endoscope moves forward and backward in an interlocking manner with this movement. Therefore, the visual field of the endoscope can be changed without asking for an assistant&#39;s help. Additionally, since the surgeon can operate the treatment tool while always grasping a surrounding situation, stress is not placed on the switching work itself of the affected part (treatment part). 
     Next, as a gallbladder neck pulling step, the assistant grips and pulls the neck of the gallbladder with the assistant treatment tool (gripping forceps) (Step S 52 ). 
     Next, as a Calot&#39;s triangle checking step, the surgeon visually checks the Calot&#39;s triangle with the endoscope, and sets a surgical field (Step S 54 ). In this case, the Calot&#39;s triangle is adjusted by the treatment tool (gripping forceps) that is pulling the gallbladder and the liver so as to become visible. 
     Next, as a cystic-duct-and-the-like peeling step, the surgeon operates the surgeon left treatment tool (5 mm gripping forceps) with the left hand, and operates the surgeon right treatment tool (5 mm peeling forceps) with the right hand, and peels a cystic duct, a cystic artery, and a cystic vein (Step S 56 ). In this case, since the peeling operation is a small operation, the stroke thereof falls within the play of the interlocking mechanism of the first trocar, and the endoscope does not interlock. Therefore, at the time of the peeling operation, a stable visual field is obtained and treatment becomes easy. Due to this peeling operation, three ducts are isolated from the liver by about 15 mm. In addition, specifically, the cystic-duct-and-the-like peeling step is performed according to the following procedure. 
     (1) The surgeon grips the cystic duct and the cystic artery and vein with the surgeon left treatment tool. 
     (2) The surgeon applies a large counter traction to the surgeon left side with the surgeon left treatment tool. 
     (3) The surgeon brings the surgeon right treatment tool close to the cystic duct and the cystic artery and vein. In this case, in an observation image of the endoscope, the cystic duct and the cystic artery and the cystic vein are gradually magnified in conformity with the forward movement of the surgeon right treatment tool. 
     (4) The surgeon performs peeling with the surgeon right treatment tool. In this case, since the pulling performed by the assistant is effective compared to the single-port (single-hole type) laparoscopic surgery, the peeling can be easily performed. Additionally, the surgeon checks whether an internal organ is penetrated with the surgeon right treatment tool during the peeling. 
     In addition, in the cystic-duct-and-the-like peeling step, when the cystic duct, the cystic artery, and the cystic vein are bleeding at the time of the peeling thereof, the surgeon performs energization hemostasis or pressure hemostasis with gauze, and performs cleaning using a water supply suction pipe. In addition, the surgeon wipes the endoscope and cleans the distal end thereof when the endoscope is soiled and fog is generated. Additionally, the endoscope may be soaked in hot water or may be coated with a defogger. 
     Next, as a cystic-duct-and-the-like ligation step, the surgeon ligates the cystic duct, the cystic artery, and the cystic vein in three places (one place on a removed organ side and two places on the body side) with 5 mm clips (Step S 58 ). As treatment tools to be used in this case, the surgeon left treatment tool is 5 mm gripping forceps, and the surgeon right treatment tool is 5 mm clips. 
     Next, as a cystic-duct-and-the-like incision step, the surgeon incises the cystic duct, the cystic artery, and the cystic vein while performing mono-polar energization to the cystic duct, the cystic artery, and the cystic vein with the surgeon right treatment tool (5 mm scissors forceps) (Step S 60 ). In this case, the incision is performed between clips in one place on the removed organ side and two places on the body side. 
     Next, as a gallbladder peeling step, the surgeon peels the gallbladder with the 5 mm peeling forceps (Step S 62 ). In this case, the peeling proceeds from the bottom of the gallbladder to the neck thereof. Additionally, as treatment tools to be used in this case, the surgeon left treatment tool is 5 mm gripping forceps, and the surgeon right treatment tool is 5 mm peeling forceps. In addition, specifically, the cystic-duct-and-the-like incision step is performed according to the following procedure. 
     (1) The surgeon applies counter traction to an upper part with the surgeon left treatment tool. 
     (2) The endoscope is brought close to a peeling surface before the surgeon performs peeling with the surgeon right treatment tool. In this case, although the visual field of the endoscope becomes narrow, this is effective because a place to be peeled is followed. That is, operation is simple. Additionally, the relative positions of the endoscope and the surgeon right treatment tool can be changed as desired by the surgeon, and the setting adapted to the procedure of the surgeon is allowed. 
     (3) The surgeon performs energization removal while gripping the peeling surface with the surgeon right treatment tool. In addition, when the surgeon changes a gripping portion of the surgeon left treatment tool, the change is made while the gallbladder is held down with the surgeon right treatment tool. 
     (4) The peeling of the gallbladder is completed by repeating the above. 
     In addition, in the gallbladder peeling step, when the gallbladder is bleeding at the time of the peeling, the surgeon performs energization hemostasis or pressure hemostasis with gauze, and performs cleaning using the water supply suction pipe. In addition, the surgeon wipes the endoscope and cleans the distal end thereof when the endoscope is soiled and fog is generated. Additionally, the endoscope may be soaked in hot water or may be coated with a defogger. 
     Next, as a cleaning step, the surgeon cleans a liver-isolated portion with the water supply suction pipe after the isolation of the gallbladder (Step S 64 ). 
     Next, as a checking step, the surgeon observes the liver-isolated portion with the endoscope, and performs checking about the presence/absence of bleeding, bile leakage, the presence/absence of liver damage, and the like, the inside of the entire abdominal cavity is further observed, and it is checked that there is no other internal organ damage (Step S 66 ). 
     The gallbladder treatment step is completed as described above. 
     [Extraction Step] 
     Next, as an extraction step, the endoscope, the treatment tool, and the first to third trocars are extracted according to a predetermined order (Step S 28 ). In this case, the surgeon grips the gallbladder with the treatment tool, and removes the gallbladder to the outside of the body when the trocars are extracted. 
     [Post-Treatment Step] 
     Next, as a post-treatment step, the surgeon and the assistant ligate and suture two places of an incised part, and arrange a drain in one place of the incised part (Step S 30 ). Additionally, a pore part may be closed with an adhesive. 
     Thereafter, after predetermined work (clearing-up or the like) has been performed, the laparoscopic gallbladder removal surgery is completed. 
     (Laparoscopic Kidney Removal Surgery) 
     Next, laparoscopic kidney removal surgery will be described as a second example of the endoscopic surgery. 
       FIGS. 33 and 34  are schematic views illustrating a situation in which the laparoscopic kidney removal procedure is performed. In addition,  FIG. 33  illustrates the situation of the outside of a patient and  FIG. 34  illustrates the situation of the inside of the patient&#39;s body cavity. As illustrated in these drawings, in the laparoscopic kidney removal surgery using the endoscopic surgical device  10  of the present embodiment, similar to the above-described laparoscopic gallbladder removal surgery, holes (ports) for allowing the endoscope and the treatment tool to be inserted into the abdominal cavity therethrough are formed in three places in the patient&#39;s abdomen. That is, in the present embodiment, the endoscope (equivalent to the above endoscope  100 ) and the treatment tool (equivalent to the above treatment tool  200 ) are inserted into the body cavity via the overtube (the first trocar equivalent to the above overtube  300 ) from the same port. Therefore, the number of ports is smaller by one compared to related-art multi-port (multi-hole type) laparoscopic kidney removal surgery. 
       FIG. 35  is a view illustrating a procedure of the laparoscopic kidney removal surgery. Additionally,  FIG. 36  is a view illustrating a procedure of a kidney treatment step. In addition, in  FIGS. 35 and 36 , the same reference signs will be given to the same steps as those of  FIGS. 31 and 32 , and the description thereof will be omitted or simply described. 
     First, as illustrated in  FIG. 35 , similar to the laparoscopic kidney removal surgery, the respective steps from Step S 10  to Step S 24 , that is, the prior preparation step, the first trocar insertion step, the pneumoperitoneum step, the endoscope insertion step, the second trocar insertion step, the third trocar insertion step, the observation step, and the treatment tool insertion step are sequentially performed. 
     In addition, in the observation step (Step S 22 ), when the main parts are observed after the entire observation has been performed, the surgeon moves the endoscope forward to an affected part side (front side), and observes a certain retroperitoneum of the kidney with the endoscope. 
     [Kidney Treatment Step] 
     Next, a kidney treatment step is performed (Step S 32 ). In the kidney treatment step, the surgeon peels the retroperitoneum from the inside of the patient&#39;s abdominal cavity and peels and removes the kidney. Specifically, the kidney treatment step is performed according to a procedure illustrated in  FIG. 36 . 
     That is, as illustrated in  FIG. 36 , first, a kidney exposure step is performed (Step S 70 ). In the kidney exposure step, the surgeon peels the retroperitoneum with the surgeon left treatment tool (gripping forceps) and the surgeon right treatment tool (peeling forceps), and exposes the kidney. In addition, specifically, the kidney exposure step is performed according to the following procedure. 
     (1) The surgeon operates the surgeon right treatment tool and picks up an image at the position of the kidney. 
     (2) The surgeon grips the retroperitoneum with the surgeon left treatment tool. 
     (3) The surgeon peels the retroperitoneum with the surgeon right treatment tool. In this case, a monopolar electrode treatment tool, a bipolar electrode treatment tool, or an ultrasonic incision treatment tool may be used. 
     (4) The assistant pulls the peeled kidney. 
     (5) The surgeon performs the above treatment and exposes the entire kidney, a kidney artery, a kidney vein, and a ureter. 
     In addition, in the present embodiment, the observation range (image pick-up range) of the endoscope may become smaller than that of the multi-port laparoscopic surgery. When it is desired to see an entire image in that case, the internal organs may be switched from one hand to the other hand again. Meanwhile, if the surgeon moves a treatment tool forward and backward, the endoscope moves forward and backward in an interlocking manner with this movement. Therefore, the visual field of the endoscope can be changed without asking for an assistant&#39;s help. Additionally, since the surgeon can operate the treatment tool while always grasping a surrounding situation, stress is not placed on the switching work itself of the affected part (treatment part). 
     Next, as a kidney pulling step, the assistant pulls the kidney with the assistant treatment tool (gripping forceps) (Step S 72 ). 
     Next, as a ureter, artery and vein checking step, the surgeon visually checks the ureter, the artery, and the vein on a main artery side with the endoscope, and installs a surgical field (Step S 74 ). In this case, an adjustment is made by the treatment tool (gripping forceps) that is pulling the kidney so that the ureter, the artery, and the vein appear. If necessary, the small intestine is moved by the treatment tool (gripping forceps) so as to be outside of the surgical field. 
     Next, as a ureter, artery and vein peeling step, the surgeon operates the surgeon left treatment tool (5 mm gripping forceps) with the left hand, and operates the surgeon right treatment tool (5 mm peeling forceps) with the right hand, and peels a ureter, a kidney artery, and a kidney vein (Step S 76 ). In this case, since the peeling operation is a small operation, that stroke falls within the play of the interlocking mechanism of the first trocar, and the endoscope does not interlock. Therefore, at the time of the peeling operation, a stable visual field is obtained and treatment becomes easy. Due to this peeling operation, three ducts are isolated by about 15 mm. In addition, specifically, the ureter, artery and vein peeling step is performed according to the following procedure. 
     (1) The surgeon grips the ureter and the kidney artery and vein with the surgeon left treatment tool. 
     (2) The surgeon applies a large counter traction to the surgeon left side with the surgeon left treatment tool. 
     (3) The surgeon brings the surgeon right treatment tool close to the ureter and the kidney artery and vein. In this case, in an observation image of the endoscope, the ureter and the kidney artery and vein are gradually magnified in conformity with the forward movement of the surgeon right treatment tool. 
     (4) The surgeon performs peeling with the surgeon right treatment tool. In this case, since the pulling performed by the assistant is effective compared to the single-port (single-hole type) laparoscopic surgery, the peeling can be easily performed. Additionally, the surgeon checks whether penetration is made, with the surgeon right treatment tool during the peeling. 
     In addition, in the ureter, artery and vein peeling step, when the ureter, the kidney artery, and the kidney vein are bleeding at the time of the peeling thereof, the surgeon performs energization hemostasis or pressure hemostasis with gauze, and performs cleaning using the water supply suction pipe. In addition, the surgeon wipes the endoscope and cleans the distal end thereof when the endoscope is soiled and fog is generated. Additionally, the endoscope may be soaked in hot water or may be coated with a defogger. 
     Next, as a ureter, artery and vein ligation step, the surgeon ligates the ureter, the kidney artery, and the kidney vein in three places (one place on the removed organ side and two places on the body side) for each with 5 mm clips (Step S 78 ). As treatment tools to be used in this case, the surgeon left treatment tool is 5 mm gripping forceps, and the surgeon right treatment tool is 5 mm clips. In this case, the ligation is performed from the artery. 
     Next, as a ureter, artery and vein incision step, the surgeon incises the ureter, the kidney artery, and the kidney vein while performing mono-polar energization to the ureter, the kidney artery, and the kidney vein with the surgeon right treatment tool (5 mm scissors forceps) (Step S 80 ). In this case, the incision is performed between clips in one place on the removed organ side and two places on the body side. 
     Next, as a kidney peeling step, the surgeon peels the kidney with the 5 mm peeling forceps (Step S 82 ). As treatment tools to be used in this case, the surgeon left treatment tool is 5 mm gripping forceps, and the surgeon right treatment tool is 5 mm peeling forceps. In addition, specifically, the kidney peeling step is performed according to the following procedure. 
     (1) The surgeon applies counter traction to an upper part with the surgeon left treatment tool. 
     (2) The endoscope is brought close to a peeling surface before the surgeon performs peeling with the surgeon right treatment tool. In this case, although the visual field of the endoscope becomes narrow, this is effective because a place to be peeled is followed. That is, operation is simple. Additionally, the relative positions of the endoscope and the surgeon right treatment tool can be changed as desired by the surgeon, and the setting adapted to the procedure of the surgeon is allowed. 
     (3) The surgeon performs energization removal while gripping the peeling surface with the surgeon right treatment tool. In addition, when the surgeon changes a gripping portion of the surgeon left treatment tool, the change is made while the kidney is held down with the surgeon right treatment tool. 
     (4) The peeling of the kidney is completed by repeating the above. 
     In addition, in the kidney peeling step, when the kidney is bleeding at the time of the peeling, the surgeon performs energization hemostasis or pressure hemostasis with gauze, and performs cleaning using the water supply suction pipe. In addition, the surgeon wipes the endoscope and cleans the distal end thereof when the endoscope is soiled and fog is generated. Additionally, the endoscope may be soaked in hot water or may be coated with a defogger. 
     Next, as a cleaning step, the surgeon cleans an isolated portion with the water supply suction pipe after the isolation of the kidney (Step S 64 ). 
     Next, as a checking step, the surgeon observes the isolated portion with the endoscope, and performs checking about the presence/absence of bleeding, the presence/absence of tissue damage, and the like, the inside of the entire abdominal cavity is further observed, and it is checked that there is no other internal organ damage (Step S 66 ). 
     The kidney treatment step is completed as described above. 
     [Extraction Step] 
     Next, as an extraction step, the endoscope, the treatment tool, and the first to third trocars are extracted according to a predetermined order (Step S 28 ). In this case, the surgeon grips the kidney with the treatment tool, and removes the kidney to the outside of the body when the trocars are extracted. In this case, a pouch may be used. Additionally, in order to take out the kidney, the skin may be additionally incised. 
     [Post-Treatment Step] 
     Next, as a post-treatment step, the surgeon and the assistant ligate and suture two places of an incised part, and arrange a drain in one place of the incised part (Step S 30 ). Additionally, a pore part may be closed with an adhesive. 
     Thereafter, after predetermined work (clearing-up or the like) has been performed, the laparoscopic kidney removal surgery is completed. 
     (Laparoscopic Uterus and Ovary Removal Surgery) 
     Next, laparoscopic uterus and ovary removal surgery will be described as a third example of the endoscopic surgery. 
     In the laparoscopic uterus and ovary removal surgery using the endoscopic surgical device  10  of the present embodiment, similar to the above-described laparoscopic gallbladder removal surgery and laparoscopic kidney removal surgery, holes (ports) for allowing the endoscope and the treatment tool to be inserted into the abdominal cavity therethrough are formed in three places in the patient&#39;s abdomen. That is, in the present embodiment, the endoscope (equivalent to the above endoscope  100 ) and the treatment tool (equivalent to the above treatment tool  200 ) are inserted into the body cavity via the overtube (the first trocar equivalent to the above overtube  300 ) from the same port. Therefore, the number of ports is smaller by one compared to the related-art multi-port (multi-hole type) laparoscopic surgery. 
     Next, a procedure of the laparoscopic uterus and ovary removal surgery will be described. 
     First, in the laparoscopic uterus and ovary removal surgery, similar to the laparoscopic gallbladder removal surgery, the prior preparation step, the first trocar insertion step, the pneumoperitoneum step, the second trocar insertion step, the third trocar insertion step, the observation step, and the treatment tool insertion step are sequentially performed (refer to  FIG. 31 ). 
     In addition, in the observation step, when the main parts are observed after the entire observation has been performed, the surgeon moves the endoscope forward to an affected part side (front side), and observes the vicinity of the uterus with the endoscope. 
     Additionally, in the treatment tool insertion step, the surgeon inserts the bipolar forceps (5 mm bipolar forceps) into the second trocar as the surgeon left treatment tool, and subsequently inserts the scissors forceps (5 mm scissors forceps) into the first trocar as the surgeon right treatment tool. Subsequently, the assistant inserts the gripping forceps (5 mm gripping forceps) into the third trocar as the assistant treatment tool. 
     [Uterus Isolation Step] 
     Next, a uterus isolation step is performed. In the uterus isolation step, the surgeon isolates a patient&#39;s uterus from a round ligament of the uterus, a broad ligament of the uterus, and a suspensory ligament of the ovary. Specifically, the uterus isolation step is performed according to the following procedure. 
     First, a round-ligament-of-uterus cutting step is performed. Specifically, the vagina suturing step is performed according to the following procedure. 
     (1) The surgeon picks up an image of the left side of the uterus. 
     (2) The assistant grips a uterus strand of a left round ligament of the uterus with the assistant treatment tool (gripping forceps), and pulls the uterus strand to the right side. 
     (3) The surgeon performs bipolar energization to the round ligament of the uterus with the surgeon right treatment tool (scissors forceps), coagulates the round ligament of the uterus, and then cuts the round ligament of the uterus. 
     Next, a broad-ligament-of-uterus incision step is performed. Specifically, the vagina suturing step is performed according to the following procedure. 
     (1) The surgeon incises the broad ligament of the uterus while performing bipolar energization to the broad ligament of the uterus on a patient&#39;s front side with the surgeon right treatment tool (scissors forceps) up to a vaginal part (in front of a uterine artery). 
     (2) The surgeon incises the broad ligament of the uterus while performing bipolar energization to the broad ligament of the uterus on a patient&#39;s rear side with the surgeon right treatment tool (scissors forceps) up to the vaginal part (in front of the uterine artery). 
     (3) The surgeon incises the broad ligament of the uterus while performing bipolar energization to the broad ligament of the uterus on a patient&#39;s front side with the surgeon right treatment tool (scissors forceps) up to the suspensory ligament of the ovary. 
     (4) The surgeon incises the broad ligament of the uterus while performing bipolar energization to the broad ligament of the uterus on the patient&#39;s rear side with the surgeon right treatment tool (scissors forceps) up to the suspensory ligament of the ovary. 
     In addition, since the surgeon right treatment tool (scissors forceps) is a main procedure and the endoscope always follows the surgeon right treatment tool, the surgeon can perform a procedure smoothly without stress. 
     Next, a suspensory-ligament-of-ovary cutting step is performed. Specifically, the vagina suturing step is performed according to the following procedure. 
     (1) The assistant grips the vicinity of the uterus in the suspensory ligament of the uterus with the assistant treatment tool (gripping forceps), and pulls the vicinity of the uterus to the right side. 
     (2) The surgeon performs bipolar energization to the suspensory ligament of the ovary with the surgeon right treatment tool (scissors forceps) near the ovary, coagulates the suspensory ligament of the ovary, and then cuts the suspensory ligament of the ovary. 
     In addition, the surgeon wipes the endoscope and cleans the distal end thereof when the endoscope is soiled and fog is generated. Additionally, the endoscope may be soaked in hot water or may be coated with a defogger. 
     Next, also on the right side of the uterus, the round-ligament-of-uterus cutting step, the broad-ligament-of-uterus incision step, and the suspensory-ligament-of-ovary cutting step are similarly performed. 
     Next, a bladder peeling step is performed. Specifically, the vagina suturing step is performed according to the following procedure. 
     (1) The assistant pulls the bladder upward with the assistant treatment tool (gripping forceps). 
     (2) The surgeon isolates the bladder and the uterus, using the surgeon right treatment tool (bipolar forceps) and the surgeon left treatment tool (gripping forceps). 
     In addition, since the peeling is performed by the cooperation of the surgeon left treatment tool and the surgeon right treatment tool, the surgeon left treatment tool may deviate from the surgical field. Meanwhile, since a closed procedure is performed by one surgeon (there is no cooperation with the assistant), the surgeon can perform a procedure smoothly without stress. 
     [Uterus Cutting Step] 
     Next, a uterus cutting step is performed. In a uterus cutting step, the uterine artery is coagulated and cut, and the uterus is cut off from a vagina. In addition, the uterus cutting step is performed according to the following procedure. 
     First, a uterine-artery cutting step is performed. Specifically, the vagina suturing step is performed according to the following procedure. 
     (1) The assistant pulls the uterus to a patient&#39;s right side with the assistant treatment tool (gripping forceps), and the surgeon picks up an image of a uterine artery part of a uterus root. 
     (2) The position of the ureter is checked so that the ureter is not erroneously damaged. 
     (3) The surgeon coagulates and cuts the uterine artery with the surgeon right treatment tool (bipolar forceps). 
     (4) The right side of the uterus is similarly treated. 
     Next, a uterus removal step is performed. Specifically, the vagina suturing step is performed according to the following procedure. 
     (1) The surgeon cuts the vagina from the upper side of the vagina along a guide of a manipulator for a uterus with the surgeon left treatment tool (hook forceps). 
     (2) The surgeon appropriately stops bleeding with the surgeon right treatment tool (peeling forceps). 
     (3) The assistant pulls the uterus rightward with the assistant treatment tool (gripping forceps), and the surgeon cuts the left side (about 180°) of the vagina with the surgeon left treatment tool (hook forceps). 
     (4) The right side of the vagina is similarly treated. 
     (5) Since the uterus cannot be pulled to the left side, the surgeon cuts the right side of the vagina with the surgeon right treatment tool (hook forceps) while holding down the uterus on the left side with the belly part of the surgeon left treatment tool (peeling forceps). 
     (6) The assistant takes out the uterus from the vagina to the outside of the body together with the manipulator for a uterus. 
     In addition, in the uterus removal step, when there is bleeding, the surgeon performs energization hemostasis or pressure hemostasis with gauze, and performs cleaning using the water supply suction pipe. In addition, the surgeon wipes the endoscope and cleans the distal end thereof when the endoscope is soiled and fog is generated. Additionally, the endoscope may be soaked in hot water or may be coated with a defogger. 
     Next, the vagina suturing step is performed. Specifically, the vagina suturing step is performed according to the following procedure. 
     (1) The surgeon sutures a mucous membrane of the vagina. 
     (2) The surgeon sutures the peritoneum and a sacral uterine ligament. 
     The uterus removal step is completed as described above. 
     [Extraction Step] 
     Next, as an extraction step, the endoscope, the treatment tool, and the first to third trocars are extracted according to a predetermined order. 
     [Post-Treatment Step] 
     Next, as a post-treatment step, the surgeon and the assistant ligate and suture two places of an incised part, and arrange a drain in one place of the incised part. Additionally, a pore part may be closed with an adhesive. 
     Thereafter, after predetermined work (clearing-up or the like) has been performed, the laparoscopic uterus and ovary removal surgery is completed. 
     (Laparoscopic Appendix Removal Surgery) 
     Next, laparoscopic appendix removal surgery will be described as a fourth example of the endoscopic surgery. 
     In the laparoscopic appendix removal surgery using the endoscopic surgical device  10  of the present embodiment, holes (ports) for allowing the endoscope and the treatment tool to be inserted into the abdominal cavity therethrough are formed in two places in the patient&#39;s abdomen. That is, in the present embodiment, the endoscope (equivalent to the above endoscope  100 ) and the treatment tool (equivalent to the above treatment tool  200 ) are inserted into the body cavity via the overtube (the first trocar equivalent to the above overtube  300 ) from the same port. Therefore, the number of ports is smaller by one compared to related-art multi-port (multi-hole type) laparoscopic appendix surgery. 
     First, in the laparoscopic appendix removal surgery, similar to the laparoscopic gallbladder removal surgery, the prior preparation step, the first trocar insertion step, the pneumoperitoneum step, the second trocar insertion step, the observation step, and the treatment tool insertion step are sequentially performed (refer to  FIG. 31 ). In the laparoscopic appendix removal surgery, the number of ports is two as described above. Therefore, the third trocar insertion step as in the laparoscopic gallbladder removal surgery is not performed. 
     In addition, in the observation step, when the main parts are observed after the entire observation has been performed, the surgeon moves the endoscope forward to an affected part side (front side), and observes the vicinity of the appendix with the endoscope. 
     Additionally, in the treatment tool insertion step, the surgeon inserts the gripping forceps (5 mm gripping forceps) into the second trocar as the surgeon left treatment tool, and subsequently inserts the gripping forceps (5 mm gripping forceps) into the first trocar as the surgeon right treatment tool. 
     [Appendix Peeling Step] 
     Next, an appendix peeling step is performed. In the appendix peeling step, the surgeon peels a patient&#39;s appendix from a mesoappendix. Specifically, the appendix peeling step is performed according to the following procedure. 
     First, the surgeon finds an appendix buried in the intestines using the surgeon left treatment tool and the surgeon right treatment tool (that is, the left and right gripping forceps), and lifts the appendix so that treatment is easily performed. Next, after the surgeon right treatment tool has been replaced with peeling forceps from the gripping forceps, the mesoappendix is separated with the surgeon right treatment tool (peeling forceps) while the appendix is lifted with the surgeon left treatment tool (gripping forceps). Here, since a closed procedure is performed by one surgeon (there is no cooperation with the assistant), the treatment of the pulling and the peeling can be smoothly performed without stress. 
     In addition, the surgeon wipes the endoscope and cleans the distal end thereof when the endoscope is soiled and fog is generated. Additionally, the endoscope may be soaked in hot water or may be coated with a defogger. 
     [Appendix Removal Step] 
     Next, appendix removal is performed. Specifically, the appendix removal is performed according to the following procedure. 
     (1) The appendix is pulled with the surgeon left treatment tool (gripping forceps). 
     (2) The surgeon ligates the root of the appendix twice. 
     (3) A side where the appendix is removed is ligated. 
     (4) The surgeon right treatment tool is replaced with scissors forceps. 
     (5) The appendix is cut so that the twice ligation side remains inside the body. 
     The appendix removal step is completed as described above. 
     [Extraction Step] 
     Next, as an extraction step, the endoscope, the treatment tool, and the first and second trocars are extracted according to a predetermined order. In this case, the surgeon grips the appendix with the treatment tool, and removes the appendix to the outside of the body when the trocars are extracted. 
     [Post-Treatment Step] 
     Next, as a post-treatment step, the surgeon and the assistant ligate and suture one place of an incised part, and arrange a drain in one place of the incised part. Additionally, a pore part may be closed with an adhesive. 
     Thereafter, after predetermined work (clearing-up or the like) has been performed, the appendix removal surgery is completed. 
     Although the endoscopic surgical device and the overtube related to the invention has been described above in detail, the invention is not limited to the above embodiments, and various improvements and modifications may be made without departing from the scope of the invention. 
     EXPLANATION OF REFERENCES 
     
         
         
           
               10 : endoscopic surgical device 
               100 : endoscope 
               102 : endoscope insertion part 
               104 : operating part 
               106 : universal cable 
               108 : processor device 
               110 : light source device 
               112 : monitor 
               120 : pneumoperitoneum device 
               122 : air supply tube 
               150 : smaller-diameter part 
               152 : larger-diameter part 
               154 : stepped part 
               170 : high-friction part 
               200 : treatment tool 
               202 : treatment tool insertion part 
               204 : operating part 
               206 : treatment part 
               208 : sheath 
               210 : fixed handle 
               214 : movable handle 
               300 : overtube 
               300   a : reference axis 
               302 : base end surface 
               304 : distal end surface 
               306 : endoscope insertion passage 
               306   a : endoscope insertion axis 
               308 : treatment tool insertion passage 
               308   a : treatment tool insertion axis 
               310 : endoscope insertion opening 
               312 : endoscope delivery opening 
               314 : treatment tool insertion opening 
               316 : treatment tool delivery opening 
               318 : air supply connector 
               320 : overtube body 
               322 : outer wall 
               324 : lumen 
               340 : base end cap 
               342 : through-hole 
               344 : through-hole 
               346 : valve member 
               348 : valve member 
               350 : through-hole 
               360 : distal end cap 
               362 : through-hole 
               364 : through-hole 
               370 : guide groove 
               372 : guide groove 
               374 : guide plate 
               376 : guide plate 
               400 : slider (interlocking member) 
               402 : slider body 
               404 : upper surface 
               406 : lower surface 
               408 : protruding strip 
               410 : protruding strip 
               420 : endoscope-coupled part 
               422 : treatment tool-coupled part 
               424 : through-hole 
               426 : pressure-contact member 
               426   e : rear end 
               428 : pressure-contact member attachment part 
               430 : opening 
               432 : through-hole 
               440 : sleeve (sleeve member) 
               444 : sleeve body (frame body) 
               446 : pressure-contact member 
               448 : through-hole 
               450 : through-hole 
               460 : guide part 
               462 : guide surface 
               464 : sleeve housing space 
               466 : end edge part 
               468 : end edge part 
               470 : guide rod 
               472 : guide rod 
               474 : guide hole 
               476 : guide hole 
               500 : inner needle 
               502 : rod part 
               504 : rod part 
               506 : distal end part 
               508 : distal end part 
               510 : head part 
               512 : head part body 
               514 : locking lever 
               520 : axis 
               522 : side surface 
               524 : lower surface 
               528 : front end surface 
               532 : locking claw 
               534 : locking hole