Patent Publication Number: US-2022233198-A1

Title: Endoscopic treatment device

Description:
TECHNICAL FIELD 
     The present disclosure relates to an endoscopic treatment device, more specifically, relates to an endoscopic treatment device including a clip unit for ligating tissues. 
     This application claims benefit of U.S. Provisional Application No. 63/141,620, filed on Jan. 26, 2021, PCT International Application No. PCT/JP2021/008932, filed on Mar. 8, 2021, and PCT International Application No. PCT/JP2021/009575, field on Mar. 10, 2021. The entire disclosure of the PCT International Applications and the U.S. Provisional Application are hereby incorporated by reference herein. 
    
    
     BACKGROUND ART 
     The ligation of tissues by using a clip unit is known as an endoscopic treatment. The clip unit includes a pair of arms. When the pair of arms are pulled by a predetermined amount in a state of grasping the tissues, the pair of arms are locked in a state of firmly tightening the tissues. 
     The clip unit as a treatment unit is introduced into the body in a state of being mounted on an actuator. The clip unit is indwelled in the body in a state of ligating the tissues such that it is necessary to separate the pair of arms from the actuator after being locked. 
     The clip unit disclosed in Japanese Patent (Granted) Publication No. 5750620 has a configuration in which proximal end portions of a pair of arms are accommodated in a pressing tube. The proximal end portions of the pair of arms are connected with an operation wire. 
     When the operation wire is pulled to draw the proximal end portions of the pair of arms outside of the pressing tube by a predetermined amount and then release the connection of the pair of arms and the operation wire, the pair of arms are locked in a closed state. Accordingly, until the proximal end portions of the pair or arms are drawn outside of the pressing tube by the predetermined amount, it is possible to push the operation wire so as to open the pair of arms which are half closed. 
     SUMMARY 
     According to an aspect of the present disclosure, a clip device includes a clip including a plurality of arms having sliding grooves respectively; and an intermediate member inserted into the sliding grooves for connecting the plurality of arms; a pressing tube configured to accommodate a proximal end portion of the clip; a connection member configured to connect with an operation wire at a proximal end side and including an engaging portion to engage with the intermediate member; and a locking mechanism configured to lock the plurality of arms when the clip is pulled toward the proximal end side by a predetermined distance by the connection member, wherein the clip further includes a contact portion formed on a side surface of the arm, and the contact portion is configured to be in contact with the engaging portion from a direction orthogonal to an axial direction of the intermediate portion for preventing a deformation of the engaging portion during a process when the intermediate portion slides along the sliding groove before the plurality of arms are locked. 
     According to another aspect of the present disclosure, an endoscopic treatment device includes a clip including a pair of arms at a distal end side of the clip, the pair of arms being configured to freely open and close; a tubular pressing tube into which at least part of the proximal end side of the clip is inserted; a wire configured to control the open and close of the pair of arms; and a connection member configured to connect the pair of arms and the wire, wherein a tail of the pair of arms includes a snap-fit hole, and a distal end of the connection member engages with the snap-fit hole. 
     According to a further aspect of the present disclosure, a clip device includes a clip including two arms and an intermediate member inserting through a proximal end portion of the two arms to connect the two arms; and a connection member configured to connect an operation wire and the intermediate member, wherein a distal end portion of the connection member includes an engaging portion configured to engage with the intermediate member, the connection member includes a contact portion extending from the engaging portion to a lateral position of the arms while the contact portion being in contact with the arms from the lateral side in a state in which the engaging portion is engaged to the intermediate member, and a width of the contact portion is larger than a width of other portions of the connection member. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a view showing an overall configuration of an endoscopic treatment device according to a first embodiment of the present disclosure. 
         FIG. 2  is a view showing a clip unit of the endoscopic treatment device. 
         FIG. 3  is a cross-sectional view showing the clip unit. 
         FIG. 4  is a cross-sectional view showing the clip unit from a different direction from that in  FIG. 3 . 
         FIG. 5  is a view showing connection procedures of a slider and a wire. 
         FIG. 6  is an enlarged cross-sectional view showing a portion of the endoscopic treatment device for mounting the clip thereto. 
         FIG. 7  is an enlarged view of a hook. 
         FIG. 8  is an enlarged view showing an engagement portion of the hook and the arm portion. 
         FIG. 9  is a view showing a state in which it is difficult to release the connection of the hook and the arm portion, and  FIG. 9  is not a view showing the present endoscopic treatment device. 
         FIG. 10  is a view showing a modification example of the hook. 
         FIG. 11  is a view showing a modification example of the hook. 
         FIG. 12  is a view showing a modification example of an operation portion main body. 
         FIG. 13  is a view showing an engagement portion of the hook and the arm portion in a modification example. 
         FIG. 14  is aside view schematically showing a clip device according to a second embodiment. 
         FIG. 15A  is a side view showing a first connection member according to the second embodiment. 
         FIG. 15B  is a view showing the first connection member viewed from a direction indicated by the arrow S shown in  FIG. 15A . 
         FIG. 16  is a side view showing a clip unit of the clip device according to the second embodiment which is viewed from an opposite side surface from the side surface shown in  FIG. 14 . 
         FIG. 17A  is a side view showing a pressing tube. 
         FIG. 17B  is a view observing the pressing tube along an axial direction of the pressing tube. 
         FIG. 18A  to  FIG. 18E  are schematic views showing the grasping operation, the locking operation, and the engagement releasing operation of the clip device according to the second embodiment. 
         FIG. 19  is a schematic view showing a modification of a contact portion. 
         FIG. 20  is a side view showing a first connection member according to a third embodiment. 
         FIG. 21  to  FIG. 23  are schematic views showing the grasping operation, the locking operation, and the engagement releasing operation of the clip device according to the third embodiment. 
         FIG. 24  is a schematic view showing a modification example of a connection member according to the third embodiment. 
         FIG. 25  is a view showing a clip introducing device of a clip device according to a fourth embodiment. 
         FIG. 26  is a view showing a schematic configuration of a clip unit according to the fourth embodiment. 
         FIG. 27  is a perspective view showing a configuration of an arm of the clip unit. 
         FIG. 28  is a view showing a state in which a tail of the arm of the clip unit is engaged with the pressing tube. 
         FIG. 29  is a view showing a schematic configuration of the other clip unit as a modification example according to the fourth embodiment. 
         FIG. 30  is a perspective view showing the pressing tube of the other clip unit according to the fourth embodiment. 
         FIG. 31  is a view showing the clip unit including the pressing tube shown in  FIG. 30 . 
         FIG. 32  is a cross-sectional view showing the vicinity of the clip unit in the clip device according to the fourth embodiment. 
         FIG. 33  is a schematic view showing the pressing tube in the clip device according to the fourth embodiment. 
         FIG. 34  is a schematic view showing the connection relationship of the connection member and the arm in the clip device according to the fourth embodiment. 
         FIG. 35  is a side view showing the connection member in the clip device according to the fourth embodiment. 
         FIG. 36  is a top view showing a modification example in which the thickness of the contact portion is larger than the thickness of the hook claw that is viewed from the direction S shown in  FIG. 35 . 
         FIG. 37  is a side view showing a further modification example of the connection member in the clip device according to the fourth embodiment. 
         FIG. 38  is a side view showing a connection member in a clip device according to a fifth embodiment. 
         FIG. 39  is a top view showing a modification example in which the thickness of the contact portion is larger than the thickness of the engagement claw that is viewed from the direction S′ shown in  FIG. 38 . 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     An embodiment of the present disclosure is described by referring to  FIG. 1  to  FIG. 9 . 
       FIG. 1  is a view showing an exterior appearance of an endoscopic treatment device  1  according to the present embodiment. The endoscopic treatment device  1  includes a clip unit  10  that is indwelled in the body and an applicator  50  configured to operate the clip unit  10 . The clip unit  10  is attached to a tip end (distal end) of the applicator  50 . 
       FIG. 2  is a view showing an exterior appearance of the clip unit  10 .  FIG. 3  is a cross-sectional view of the clip unit  10 . As shown in  FIG. 2 , the clip unit  10  includes an arm portion  20  and a pressing tube (tubular member)  30  in which part of the arm portion  20  is accommodated. 
     The arm portion  20  includes a pair of arms as a first arm  21  and a second arm  22 . The first arm  21  and the second arm  22  include a claw  21   a  and a claw  22   a  at the distal end portions respectively. As shown in  FIG. 3 , the first arm  21  and the second arm  22  are connected with each other at a proximal end portion  20   a  of the arm portion  20 . The proximal end portion  20   a  is formed in a U-shape. 
     The arm portion  20  is made of an alloy material or a metal material. Examples of the material of the arm portion  20  include the stainless steel, the cobalt-chromium alloy, the nickel-titanium alloy, and the like. 
     The first arm  21  and the second arm  22  are expanded to be open in an initial state as shown in  FIG. 2 . The first arm  21  and the second arm  22  are configured to generate a biasing force to return to the initial state due to the elastic force of the material when the first arm  21  and the second arm  22  approach each other from the initial state. 
     The pressing tube  30  is a tubular member made of a metal material, a resin or the like. As shown in  FIG. 3 , the proximal end portion  20   a  of the arm portion  20  is accommodated in the pressing tube  30 . The distal end portion of the arm portion  20  is configured to protrude from a distal end opening  30   a  of the pressing tube  30 . A proximal end opening  30   b  of the pressing tube  30  is smaller than the distal end opening  30   a.    
       FIG. 4  is a view showing the interior of the pressing tube  30  that is viewed from a different direction from that in  FIG. 3 . As shown in  FIG. 4 , a locking portion  23  is provided in an intermediate portion of each arm of the arm portion  20 , and a dimension of each arm  21 ,  22  in the width direction at the locking portion  23  is large (only the first arm  21  can be viewed in  FIG. 4 ). Each locking portion  23  can pass through the proximal end opening  30   b  when the first arm  21  and the second arm  22  approach each other. When the first arm  21  and the second arm  22  separate from each other after passing through the proximal end opening  30   b , the locking portion  23  cannot pass through the proximal end opening  30   b . As a result, the arm portion  20  is locked in a state in which the pair of arms are closed. 
     A coil spring  31  is disposed inside the pressing tube  30 . A proximal end of the coil spring  31  is able to come into contact with a proximal end surface  32  of the pressing tube  30  including the proximal end opening  30   b.    
     A washer  35  is disposed at the distal side of the coil spring  31 . An inner diameter of the washer  35  is smaller than the inner diameter of the coil spring  31 . The distal side of the first arm  21  and the second arm  22  are larger in the width than that of the proximal end portion and the distal end side of the first arm  21  and the second arm  22  has the dimension that is impossible to enter the washer  35 . Accordingly, the washer  35  has the configuration to be in contact with the distal side rear surface of the first arm  21  and the second arm  22  such that the distal side of the first arm  21  and the second arm  22  does not enter the coil spring  31  without providing an end coil portion having a small inner diameter in the coil spring  31 . 
     For example, part of the above-described configuration of the arm portion  20  and the pressing tube  30  is known and disclosed in PCT International Publication No. WO 2014/181676; however, it is possible to apply the following modifications to the configuration. 
     The opening width of the arm portion  20  in the initial state may be appropriately changed by changing a bending angle (curvature radius) between a region inside the pressing tube  30  and a region outside the pressing tube  30  in the initial state. At this time, by decreasing the curvature radius, it is possible that the restoration property to the initial state will be reduced; however, it is possible to prevent the reduction by changing the plate thickness of the arm portion. Furthermore, it is possible to provide multiple variations with different opening widths in the initial state by only changing the curvature radius and using the same member. 
     For example, the arm portion can be manufactured by punching and bending a metal plate material; however, it is possible to chamfer the edge portion in contact with the internal surface of the pressing tube after the manufacturing so as to make the movement inside the pressing tube  30  to be smooth and prevent the wear and the damage to the pressing tube by the edge portion. 
     As shown in  FIG. 1 , the applicator  50  includes an elongated insertion portion  51 , an operation wire (power transmission member)  52  inserted through the insertion portion  51 , and an operation portion  60  connected to the insertion portion  51 . 
     The structure of the distal end side of the insertion portion  51  will be described below, with regard to the portion other than the distal end portion, for example, it is possible to adopt a sheath formed from a coil. In the case of using the coil sheath, it is preferable to process the distal and proximal end surfaces to be flat by the polishing procedure or the like. 
     The operation portion  60  includes a main body  61  connected with the insertion portion  51 , and a slider  62  attached to the main body  61  to be slidable with respect to the main body  61 . 
     As the operation wire  52 , it is possible to adopt a twisted wire made of the metal wire, for example. The proximal end portion of the operation wire  52  is connected to the slider  62 . When the slider  62  is moved with respect to the main body  61 , it is possible to advance and retract the operation wire  52  in the insertion portion  51 . 
     The connection aspect of the operation wire  52  and the slider  62  is appropriately determined, and an example will be described referring to  FIG. 5 . 
     At first, a block  101  including a penetration horizontal hole  101   a  and a bottomed vertical hole  101   b  communicating with the horizontal hole  101   a  is prepared. As shown in the part (a) of  FIG. 5 , the operation wire  52  passing through the pipe  102  for preventing the buckling is made to pass the horizontal hole  101   a.    
     As shown in the part (b) of  FIG. 5 , when the pin  103  is inserted into the vertical hole  101   b  and then the pipe  102  and the operation wire  52  are pressed toward the bottom of the vertical hole  101   b  to perform the caulking, part of the pipe  102  and the operation wire  51  are bent to enter the vertical hole  101   b . As a result, as shown in the part (c) of  FIG. 5 , even the pin  103  is removed, it is impossible for the pipe  102  and the operation wire  52  to slip out from the block  101  such that the pipe  102  and the operation wire  52  are fixed to the block  101 . 
     Thereafter, it is possible to connect the pipe  102  and the operation wire  52  to the slider  62  by assembling the block  101  to the slider  62 . 
       FIG. 6  is an enlarged view showing the distal end portion of the applicator  50  to which the clip unit  10  is attached. The clip unit  10  and the applicator  50  are detachably connected to each other by the hook (engaging portion)  70  disposed at the distal end of the operation wire  52  engaging with the proximal end portion (engaged portion)  20   a  of the arm portion  20 . 
     The distal end portion of the insertion portion  51  includes a tubular first member  55  and a tubular second member  56  attached to the distal side of the first member  55 . 
     The outer diameter of the proximal portion of the second member  56  is smaller than the inner diameter of the first member  55 , and the second member  56  is connected to the first member  55  by welding or the like in a state of entering the first member  55 . The inner diameter of the distal side of the second member  56  is larger than the outer diameter of the pressing tube  30  and the proximal portion of the pressing tube  30  enters the second member  56 . The inner diameter of the proximal side of the second member  56  is smaller than that of the distal side of the second member  56  such that the second member  56  is formed in the structure in which a step surface  56   a  is generated due to the difference of the diameters and the step surface  56   a  can support the proximal portion of the pressing tube  30 . 
     The hook  70  passes through the inside of the first member  55  and the second member  56  to enter the pressing tube  30  and the hook  70  is engaging with the proximal end portion  20   a  of the arm portion  20  inside the pressing tube  30 . 
     The hook  70  is attached to a connection member  76  fixed to the distal end of the operation wire  52  by the brazing or the like. 
       FIG. 7  is an enlarged view showing the hook  70 . The left side of  FIG. 7  is a front view of the hook  70 , and the right side thereof is the right-side view of the hook  70 . The distal side of the hook  70  includes a hook portion  71  locked to the arm portion  20 , a support portion  72  extending backwardly from the hook portion  71 , and a protrusion portion  73  formed at the boundary portion of the hook portion  71  and the support portion  72 . The support portion  72  is generally parallel to the operation wire  52 , and there is an approximately right angle formed between the proximal surface  71   a  of the hook portion  71  and the extending direction of the support portion  72 . 
     The hook portion  71  and the support portion  72  has approximately the same thickness (the thickness T 1  shown in  FIG. 7 ); however, the thickness of the protrusion portion  73  is the thickness T 2  that is larger than the thickness T 1 . The distance between the first arm  21  and the second arm  22  in the proximal end portion  20   a  of the arm portion  20  is equal to or larger than the thickness T 1  and less than the thickness T 2 . Accordingly, as shown in  FIG. 8 , the hook portion  71  enters the space between the first arm  21  and the second arm  22  to be locked to the proximal end portion  20   a . On the other side, the protrusion portion  73  interferes with the first arm  21  and the second arm  22  such that the protrusion portion  73  cannot enter the space between the first arm  21  and the second arm  22 . 
     The hook  70  having the above-described shape can be manufactured by using the plate material having the thickness T 2  to perform the forging procedure, the Metal Injection Mold (MIM) procedure or the like. 
     A stopper  53  is attached to the operation wire  52 . The shape and the dimension of the stopper  53  are determined to be impossible to enter the first member  55  such that when the stopper  53  comes into contact with the proximal end of the first member  55 , the operation wire  52  cannot advance any further. The exterior surface of the stopper  53  is chamfered such that it is difficult for the operation wire  52  to interfere with the insertion portion  51  when the operation wire  52  is advanced and retracted in the insertion portion  51 . 
     The operations when the endoscopic treatment device  1  having the above-described configuration is used will be described. The endoscopic treatment device  1  is introduced into the body through the channel of the endoscope. When the user inserts the endoscopic treatment device  1  into the endoscope, the user retracts the slider  62  by a predetermined amount so as to insert the arm portion  20  in a state in which the arm portion  20  is closed and the arm portion  20  is not locked. The clip unit  10  in which the arm portion  20  is closed and the distal end portion of the insertion portion  51  may be inserted into the endoscope in a state of being accommodated in an outer sheath that is separately prepared. 
     When the user protrudes the endoscopic treatment device  1  from the opening of the channel of the distal end portion of the endoscope and then reduces the force pulling the slider or retracting the outer sheath, the arm portion  20  advances with respect to the pressing tube  30  due to the elastic restoration force of the arm portion  20  itself and the elastic restoration force of the coil spring  31 . As a result, the pair of arms  21 ,  22  enter the open configuration in which the pair of arms  21 ,  22  are open. When the stopper  53  comes into contact with the proximal end of the first member  55 , the arm portion  20  cannot advance with respect to the pressing tube  30  such that the open configuration is maintained and the arm portion  20  does not slip out from the pressing tube  30 . 
     If the outer sheath is too short, when the outer sheath is retracted, the endoscopic treatment device  1  advances powerfully due to the above-described elastic restoration force such that it is preferable to adopt the outer sheath with the length (for example, approximately 30 millimeters) slightly shorter than the length of the insertion portion  51 . 
     When the user retracts the slider  62  with respect to the main body  61 , the operation wire  52  and the hook  70  are pulled and the arm portion  20  is retracted with respect to the pressing tube  30 . As a result, the pair of arms  21 ,  22  enters the closed configuration in which the pair of arms  21 ,  22  are closed. The user positions the tissues between the pair of arms  21 ,  22  and then close the pair of arms  21 ,  22  to ligate the tissues. Until the locking operation described below is performed, by advancing the slider  62  with respect to the main body  61 , it is possible to transition the pair of arms  21 ,  22  from the closed configuration to the open configuration. Accordingly, according to the endoscopic treatment device  1 , until the locking operation is performed, it is possible to re-grasp the tissues by operating the clip unit using the operation wire  52 . 
     Within the movement range of the operation wire  52  where the re-grasp operation is able to perform, at least part of the distal side of the hook  70  is positioned at the proximal side inside the second member  56  where the inner diameter is small such that it is impossible that the engagement of the hook  70  and the proximal end portion  20   a  is released between the re-grasp operation. 
     When it is determined that it is suitable to ligate the tissues positioned between the pair of arms  21 ,  22 , the user performs the locking operation for fixing the closed state of the arm portion  20 . During the locking operation, the user further retracts the slider  62  with respect to the main body  61  to exceed the range where it is possible to perform the re-grasp operation. When the slider  62  is retracted, the operation wire  52  is pulled and the pair of arms  21 ,  22  becomes approximately parallel to each other while grasping the tissues to enter the pressing tube  30 . Furthermore, the locking portions  23  provided in the pair of arms  21 ,  22  approach each other to become the positional relationship capable of passing through the proximal end opening  30   b  of the pressing tube  30 . 
     The pair of locking portions  23  passing through the proximal end opening  30   b  and moving to the outside of the pressing tube  30  separates from each other to become the positional relationship that is impossible to pass through the proximal end opening  30   b  again. As a result, the pair of locking portions  23  come into contact with the proximal end surface of the pressing tube  30  so as to prevent the arm portion  20  from protruding from the pressing tube  30  and the arm portion  20  is locked to maintain the closed configuration. 
     When the user further retracts the slider  62 , the arm portion  20  further retracts and the locking portion  23  passes through the proximal end opening  30   b  to move to the outside of the pressing tube  30 . Furthermore, the locking portion  23  is locked to the proximal end surface of the pressing tube  30  and the arm portion  20  is locked to be unable to open. 
     When the user further retracts the slider  62 , the distal side of the hook  70  deforms due to the retraction force. For example, the hook portion  71  deforms such that the proximal surface  71   a  and the support portion  72  enters a state to be approximately parallel to each other or the support portion  72  deforms such that the hook portion  71  rotates around the support portion  72  as a rotation center. 
     As a result, the engagement of the hook  70  and the proximal end portion  20   a  is released and the pressing tube  30  is separated from the second member  56  such that the clip unit  10  is indwelled in the tissues. 
     When the user removes the endoscope and the applicator  50  to the outside of the body, the series of procedures are finished. 
     In the endoscopic treatment device  1 , after the arm portion  20  is locked, it is possible to release the engagement between the arm portion  20  and the hook  70  by further retracting the hook  70  only such that basically, there is no case in which the hook  70  advances after the arm portion  20  is locked. However, in the case in which the user does not notice that the arm portion  20  has been locked and tries to perform the re-grasp operation, it is possible that the hook  70  is operated to advance. At this time, even the hook  70  is operated to advance, since the arm portion  20  cannot advance, it is possible that the longitudinal direction of the arm portion and the longitudinal direction of the hook are not parallel to each other. 
     In this case, as shown in  FIG. 9 , after consideration, the inventor finds that it is possible that the advanced hook  700  (this hook is not the hook included in the endoscopic treatment device  1 ) may enter the space between the first arm  21  and the second arm  22  in the proximal end portion  20   a  of the arm portion. Furthermore, in the state as shown in  FIG. 9 , it is known that it becomes significantly difficult to separate the hook  70  from the proximal end portion  20   a.    
     The inventor further studies with the configuration and successes in eliminating the possibility by providing the protrusion portion  73  in the hook  70 , wherein the protrusion portion  73  has the dimension and the size that is unable to enter the space between the first arm  21  and the second arm  22 . Accordingly, even the user accidentally advances the hook  70  after the arm portion  20  is locked, the protrusion portion  73  interferes with the proximal end portion  20   a  so as to be unable to enter the space between the first arm  21  and the second arm  22  and the state as shown in  FIG. 9  can be definitely prevented. 
     As described above, according to the endoscopic treatment device  1  described in the present embodiment, it is possible to realize the re-grasping operation of the tissues by the clip unit  10  while releasing the connection of the applicator  50  and the clip unit  10  by pulling the operation wire  52  only such that the operations become easy. Furthermore, as described above, it is possible to definitely prevent the situation in which it becomes difficult to release the connection of the applicator  50  and the clip unit  10  due to the operations after the arm portion is locked. 
     In the endoscopic treatment device  1 , the first member  55  having the large inner diameter and the second member  56  having the small inner diameter are attached to the distal end of the insertion portion  51 . Accordingly, it is possible to definitely support the pressing tube  30  by the second member  56  while applying the force with the necessary amount to the arm portion for the locking operations. As described above, when the two end surfaces of the coil sheath are processed to be flat, the force with the large amount can be stably received by the applicator  50  such that the support becomes further stable. 
     Furthermore, until the arm portion  20  is locked, the hook  70  is positioned in the portion proximal to the second member  56  where the inner diameter is further narrower such that the large displacement of the hook  70  due to the deformation is prevented and the connection state with the arm portion  20  is definitely maintained. 
     Additionally, after the arm portion  20  is locked, the hook  70  is positioned in the large space inside the first member  55  such that the space suitable for the large displacement due to the deformation is secured. As a result, it is possible to smoothly release the connection of the arm portion and the hook by the traction of the operation wire  52 . 
     Hereinbefore, one embodiment of the present disclosure has been described; however, the scope of the present disclosure is not limited to the above-described embodiment. Configurations can be added, omitted, replaced, and other modifications without departing from the spirit of the present invention. Hereinafter, several changes will be described as examples, however, other changes are possible to be applied. Two or more of these changes may be combined as appropriate. 
     The aspect of the protrusion portion is not limited to the above-described configuration. The protrusion portion  73 A provided in the hook according to the modification example as shown in  FIG. 10  is configured to protrude to only one side in the width direction (the thickness direction of the plate-shaped material). The protrusion portion  73 A may be formed by applying an impact such as the punch or the like from the opposite side besides the above-described forging and the MIM. In the case of forming the protrusion portion  73 A by the punch or the like, the opposite side of the protrusion portion  73 A becomes the concave portion such that there may be a case in which the thickness T 2  of the protrusion portion  73 A is not larger than the distance between the first arm and the second arm; however, the same effect can be achieved once the protrusion portion  73 A protrudes enough on the surface at one side. 
     The position for disposing the protrusion portion may be changed. The protrusion portion  73 B disposed in the hook according to the modification example as shown in  FIG. 11  is positioned at the proximal side of the support portion  72 . Even in such a configuration, it is possible to prevent the whole hook from entering the space between the first arm and the second arm. 
     The power transmission member according to the present disclosure is not limited to the above-described wire. For example, in a case in which the present disclosure is applied to the treatment device used with the laparoscope, the power transmission member may be a rigid rod. 
     In the endoscopic treatment device according to the present disclosure, the structure of the engaging portion and the engaged portion may be reversed. For example, the hook may be disposed at the proximal end portion of the arm portion, and the structure in a U-shape or a loop shape that is engageable with the hook may be disposed at the distal end portion of the operation wire. 
     The modification example of the arm portion and the operation wire in which the structure of the engaging portion and the engaged portion is reversed is shown in  FIG. 13 . As shown in  FIG. 13 , the hook  70  having the protrusion portion  73  is disposed in the proximal end portion  120   a  of the arm portion  120 , and the hook  70  is engaged with the U-shaped engaged portion  152   a  disposed at the distal end of the operation wire  152 . The same effect with the above-described embodiment may be achieved by such a configuration. 
     In the endoscopic treatment device according to the present disclosure, the structure configured to attach a new clip unit to perform the indwell procedures again after indwelling the clip unit may be applied. In this case, the configuration in which the hook is elastically deformed to release the connection with the arm portion, or as described above, the configuration in which the structure of the engaging portion and the engaged portion is reversed is preferable. The structure as shown in  FIG. 13  is suitable for the case of adopting the structure in which the hook is plastic deformed to release the connection while it is possible to reload a new clip unit. 
     In the endoscopic treatment device according to the present disclosure, when the connection of the applicator and the clip unit is released, the large force is applied to the main body  61  of the operation portion  60 . For example, the main body  61  may be formed by integrating two members by snap-fitting or the like, wherein the two members have a shape obtained by dividing a cylinder made of resin or the like into half. At this time, similar to the main body  61 A according to the modification example as shown in  FIG. 12 , the protrusion  612  is provided in the first half-divided member  611 , and once the first half-divided member  611  and the second half-divided member  616  are integrated in the state in which the protrusion  612  enters the concave portion  617  provided in the second half-divided member  616 , it is possible to prevent the first half-divided member  611  and the second half-divided member  616  from being unintentionally separated from each other when the large force is applied to the main body. 
     Second Embodiment 
     The endoscopic treatment device according to the present embodiment is a clip device. As shown in  FIG. 14 , the clip device includes a clip unit  10 A indwelled in the body and an applicator  50 A configured to operate the clip unit  10 A. 
     The clip unit  10 A includes a clip  20 A and a pressing tube  30 A configured to accommodate part of the clip  20 A. 
     The clip  20 A includes a fixed arm  21 A positioned at the center and two movable arms  22 Aa,  22 Ab positioned at two sides of the fixed arm  21 A. The movable arms  22 Aa,  22 Ab are configured to be able to open and close independently from the fixed arm  21 A. 
     The movable arm  22 A is connected to the fixed arm  21 A by a first pin  23 A 1  to be rotatable. A first sliding groove  22 Aa 1  is provided in the proximal end portion of the movable arm  22 Aa. A second pin  24 A 1  is inserted into the first sliding groove  22 Aa 1 . The second pin  24 A 1  is connected to a first hook claw  40 Aa 1  (first engaging portion) of a first connection member  40 Aa. 
     A protrusion portion  22 Aa 2  for locking the clip  20 A is provided in the proximal end portion of the movable arm  22 Aa.  FIG. 15A  is the side view of the movable arm  22 Aa. In  FIG. 15A , the protrusion portion  22 Aa 2  extends along the direction orthogonal to the longitudinal direction of the movable arm  22 Aa.  FIG. 15B  is the view of observing the movable arm  22 Aa from the direction indicated by the arrow S in  FIG. 15A . In  FIG. 15B , in the case in which there is no external force is applied, the protrusion portion  22 Aa 2  extends diagonally in the direction separating away from the fixed arm  21 A. The protrusion portion  22 Aa 2  is able to elastically deform in the direction of approaching the fixed arm  21 A. 
     As shown in  FIG. 16 , the movable arm  22 Ab is connected to the fixed arm  21 A by a third pin  23 A 2  to be rotatable. A second sliding groove  22 Ab 1  is provided in the proximal end portion of the movable arm  22 Ab. A fourth pin  24 A 2  is inserted into the second sliding groove  22 Ab 1 . The fourth pin  24 A 2  is connected to a second hook claw  40 Ab 1  (second engaging portion) of a second connection member  40 Ab. A protrusion portion  22 Ab 2  for locking the clip  20 A is provided in the proximal end portion of the movable arm  22 Ab. The structure of the protrusion portion  22 Ab 2  is the same with that of the protrusion portion  22 Aa 2 , and the duplicate description will be omitted. 
     The pressing tube  30 A is configured to accommodate the proximal end portion of the fixed arm  21 A and the proximal end portions of the movable arms  22 Aa,  22 Ab. As shown in  FIG. 17A , two groove portions  30 A 1 ,  30 A 2  opposite to the circumferential direction of the pressing tube  30 A are provided at the distal end of the pressing tube  30 A. When the movable arms  22 Aa,  22 Ab are open and closed, the movable arms  22 Aa,  22 Ab pass through the groove portions  30 A 1 ,  30 A 2 , respectively. As shown in  FIG. 17B , inside the pressing tube  30 A, stopper portions  30 A 3 ,  30 A 4  being able to contact with the above-described protrusions  22 Aa 2 ,  22 Ab 2  are provided in the edge portions of the groove portions  30 A 1 ,  30 A 2 . The stopper portions  30 A 3 ,  30 A 4  form the flat stopper surfaces in the edge portions of the groove portions  30 A 1 ,  30 A 2 . 
     The protrusion portions  22 Aa 2 ,  22 Ab 2  are configured to be unable to come out from the groove portions  30 A 1 ,  30 A 2  after contacting with the stopper portions  30 A 3 ,  30 A 4 . At this time, the movable arms  22 Aa,  22 Ab cannot be open again such that the clip  20 A is locked to the pressing tube  30 A. 
     As shown in  FIG. 14 , the applicator  50 A includes an insertion portion  51 A, an operation portion  60 A, and operation wires  62 Aa,  62 Ab. The insertion portion  51 A is an elongated member inserted into the body, wherein the proximal end thereof is connected to the operation portion  60 A, and the distal end thereof is detachably connected to the pressing tube  30 A. The main body portion of the operation portion  60 A are divided into two portions and two sliders  61 Aa,  61 Ab are provided in the two portions respectively. Proximal ends of operation wires  62 Aa,  62 Ab are connected to the sliders  61 Aa,  61 Ab, respectively. The operation wires  62 Aa,  62 Ab are inserted through the inner cavity of the insertion portion  51 A, and distal ends thereof are connected to the first connection member  40 Aa and the second connection member  40 Ab, respectively. 
     The first connection member  40 Aa and the second connection member  40 Ab are elongated members inserting through the pressing tube  30 A. The proximal end of the first connection member  40 Aa is connected to the distal end of the operation wire  62 Aa. A first hook claw  40 Aa 1  is provided at the distal end of the first connection member  40 Aa. The first hook claw  40 Aa 1  engages with the second pin  24 A 1  inserted into the first sliding groove  22 Aa 1  of the movable arm  22 Aa. The proximal end of the second connection member  40 Ab is connected to the distal end of the operation wire  62 Ab. A second hook claw  40 Ab 1  is provided at the distal end of the second connection member  40 Ab. The second hook claw  40 Ab 1  engages with the fourth pin  24 A 2  inserted into the second sliding groove  22 Ab 1  of the movable arm  22 Ab. Each of the first hook claw  40 Aa 1  and the second hook claw  40 Ab 1  is formed in a C-shape. 
     Hereinafter, the movable arm  22 Aa will be taken as an example to describe the grasping operation, the locking operation, and the engagement releasing operation of the movable arm. The operations of the movable arm  22 Ab is the same with that of the movable arm  22 Aa. 
     As shown in  FIG. 18A , when the movable arm  22 Aa is open with respect to the fixed arm  21 A, the second pin  24 A 1  is positioned at the distal end of the first sliding groove  22 Aa 1 . After placing the target tissues between the movable arm  22 Aa and the fixed arm  21 A, when the slider  62 Aa is moved toward the proximal end side in the operation portion  60 A, the operation wire  62 Aa is pulled toward the proximal end side and the second pin  24 A 1  is moved toward the proximal end side in the first sliding groove  22 Aa 1 . Accordingly, the movable arm  22 Aa is rotated toward the fixed arm  21 A side (that is, the closing direction). 
     As the second pin  24 A 1  slides toward the proximal end side of the first sliding groove  22 Aa 1 , the proximal end portion of the movable arm  22 Aa moves into the inner cavity of the pressing tube  30 A through the groove portion  30 A 1 . At this time, as shown in  FIG. 18B , the protrusion portion  22 Aa 2  is pressed by the edge portion of the groove portion  30 A 1  such that the protrusion portion  22 Aa 2  is elastically deformed to the fixed arm side (the right side in  FIG. 18B ). 
     When the protrusion portion  22 Aa 2  completely enters the inner cavity of the pressing tube  30 A, the protrusion portion  22 Aa 2  is not pressed by the edge portion of the groove portion  30 A 1  so as to restore to the slanted state in the direction away from the fixed arm side (the left side in  FIG. 18C ). At this time, as shown in  FIG. 18C , the end of the protrusion portion  22 Aa 2  comes into contact with the stopper portion  30 A 3  of the pressing tube  30 A and it is impossible to come out from the groove portion  30 A 1  again. Accordingly, as shown in  FIG. 18D , the movable arm  22 Aa is locked to be impossible to open again. 
     After the movable arm  22 Aa is locked, when the operation wire  62 Aa is further pulled toward the proximal end side, the second pin  24 A 1  moves toward the proximal end of the first sliding groove  22 Aa 1 . The second pin  24 A 1  reaching the proximal end of the first sliding groove  22 Aa 1  does not further move to the proximal end side such that the reaction force from the second pin  24 A 1  and received by the first hook claw  40 Aa 1  increases. As shown in  FIG. 18E , when the reaction force from the second pin  24 A 1  and received by the first hook claw  40 Aa 1  exceeds the predetermined threshold value, the first hook claw  40 Aa 1  deforms and the engagement of the first hook claw  40 Aa 1  and the second pin  24 A 1  is released. 
     During the process of actually using the clip device, due to the manufacturing variations, there is also variations in the strength of the first hook claw  40 Aa 1  and the second hook claw  40 Ab 1 . Accordingly, there is a situation in which the hook claw firstly deforms before the movable arm is locked and the engagement of the connection member and the arm is unintentionally released. In order to prevent such a situation, contact portions described below are provided in the two movable arms. The structure of the contact portions provided in the two movable arms are the same, and the movable arm  22 Aa will be taken as an example for description. 
     As shown in  FIG. 14 ,  FIG. 15 , and  FIG. 18A , the contact portion  22 Aa 3  is formed on the side surface of the movable arm  22 Aa. The contact portion  22 Aa 3  is formed along the first sliding groove  22 Aa 1  and at a certain distance from the first sliding groove  22 Aa 1 . During the process when the second pin  24 A 1  slides along the first sliding groove  22 Aa 1 , part of the first hook claw  40 Aa 1  positions between the contact portion  22 Aa 3  and the second pin  24 A 1 , and the contact portion  22 Aa 3  is in contact with the first hook claw  40 Aa 1  in the direction orthogonal to the axial direction of the second pin  24 A 1 . Accordingly, it is possible to prevent the first hook claw  40 Aa 1  from receiving the reaction force from the second pin  24 A 1  to be deformed. 
     As shown in  FIG. 15 a   , the contact portion  22 Aa 3  is an elongated convex portion formed to protrude from the side surface of the movable arm  22 Aa. Otherwise, as shown in  FIG. 19 , the contact portion  22 Aa 3  may be a step portion formed by a partial region (the shadow region) on the side surface of the movable arm  22 Aa further raising from the sliding passage region of the first hook claw  40 Aa 1 . 
     As shown in  FIG. 18D , in the longitudinal direction of the movable arm  22 Aa, the most proximal end of the contact portion  22 Aa 3  is formed at the position where the second pin  24 A 1  is located when the movable arm  22 Aa is locked. After the movable arm  22 Aa is locked, during the process when the second pin  24 A 1  continues to move to the proximal end side of the first sliding groove  22 Aa 1  and at the time when the second pin  24 A 1  is positioned at the proximal end of the first sliding groove  22 Aa 1 , the first hook claw  40 Aa 1  is not in contact with the contact portion  22 Aa 3  anymore. Accordingly, as shown in  FIG. 18E , after the movable arm  22 A is locked, it is permitted that the first hook claw  40 Aa 1  is deformed and the engagement with the second pin  24 A 1  is released. 
     Third Embodiment 
     Compared with the second embodiment, the structure of the first engaging portion and the second engaging portion according to the third embodiment are different. Other structure thereof is the same with that of the second embodiment. 
       FIG. 20  is a side view showing a first connection member  40 Ba according to the third embodiment. The first engaging portion  40 Ba 1  formed from a first engaging claw  40 Ba 11  and a second engaging claw  40 Ba 12  is provided at the distal end of the first connection member  40 Ba. 
     The first engaging claw  40 Ba 11  and the second engaging claw  40 Ba 12  are provided to be opposite to each other. An accommodation hole  40 Ba 13  and a notch  40 Ba 13  are formed between the first engaging claw  40 Ba 11  and the second engaging claw  40 Ba 12 . 
     When the first engaging portion  40 Ba 1  and the second pin  24 B 1  are engaged with each other, the accommodation hole  40 Ba  13  is configured to accommodate the second pin  24 B 1 . 
     The distance between the first engaging claw  40 Ba 11  and the second engaging claw  40 Ba 12  in the notch  40 Ba 14  is larger than the outer diameter of the second pin  24 B 1 . The first engaging claw  40 Ba 11  and the second engaging claw  40 Ba 12  have a certain elasticity and can be expanded with respect to each other. Accordingly, the second pin  24 B 1  can be pressed into the accommodation hole  40 Ba 13  via the notch  40 Ba 14  to make the first engaging portion  40 Ba 1  and the second pin  24 B 1  to be engaged with each other. On the other side, the second pin  24 B 1  in the accommodation hole  40 Ba 13  can be disengaged from the first engaging portion  40 Ba 1  via the notch  40 Ba 14  to disengage the engagement between the first engaging portion  40 Ba 1  and the second pin  24 B 1 . 
     The structure of the second connection member is the same with that of the first connection member  40 Ba, and the duplicate description will be omitted. 
     During the process of actually using the clip device, due to the manufacturing variations, there is also variations in the strength of the engaging claws. Accordingly, there is a situation in which the engaging claw firstly deforms before the movable arm is locked and the engagement is unintentionally released. In order to prevent such a situation, contact portions described below are provided in the two movable arms. The structure of the contact portions provided in the two movable arms are the same, and the movable arm  22 Ba will be taken as an example for description. 
     As shown in  FIG. 21 , the contact portion  22 Ba 3  is formed on the side surface of the movable arm  22 Ba. The contact portion  22 Ba 3  is formed along the first sliding groove  22 Ba 1  and at a certain distance from the first sliding groove  22 Ba 1 . During the process when the second pin  24 B 1  slides along the first sliding groove  22 Ba 1 , part of the first engaging claw  49 Ba 11  positions between the contact portion  22 Ba 3  and the second pin  24 B 1 , and the contact portion  22 Ba 3  is in contact with the first engaging claw  40 Ba 11  in the direction orthogonal to the axial direction of the second pin  24 B 1 . Accordingly, it is possible to prevent the first engaging claw  40 Ba 1  from receiving the reaction force from the second pin  24 B 1  to be deformed. 
     Similar to the second embodiment, the contact portion  22 Ba 3  may be the elongated convex portion formed to protrude from the side surface of the movable arm  22 Ba, or may be the step portion formed by a partial region on the side surface of the movable arm  22 Ba further raising from the sliding passage region of the first engaging claw  40 Ba 11 . 
     In the longitudinal direction of the movable arm  22 Ba, the most proximal end of the contact portion  22 Ba 3  is formed at the position where the second pin  24 B 1  is located when the movable arm  22 Ba is locked. Accordingly, as shown in  FIG. 22 , when the movable arm  22 Ba is locked, the second pin  24 B 1  can come into contact with the contact portion  22 Ba 3  again. 
     After the arm  22 Ba is locked, when the second pin  24 A 1  is positioned at the proximal end of the first sliding groove  22 Ba 1 , the first engaging claw  40 Aa 11  is not in contact with the contact portion  22 Ba 3 . Accordingly, as shown in  FIG. 23 , after the movable arm  22 Ba is locked, it is permitted that the first engaging claw  40 Aa 11  is deformed and the engagement with the second pin  24 B 1  is released. 
     As shown in  FIG. 24 , it is preferable that the width of the second engaging claw  40 Ba 12  is larger than that of the first engaging claw  40 Ba 11  by providing a reinforcing portion  40 Ba 15 . The second engaging claw  40 Ba 12  is not in contact with the contact portion  22 Ba 3  such that it is possible that the second engaging claw  40 Ba 12  is deformed before the movable arm  22 Ba is locked and the engagement with the second pin  24 B 1  is released. It is possible to prevent the second engaging claw  40 Ba 12  that is not in contact with the contact portion  22 Ba 3  from being deformed before the movable arm  22 Ba is locked by increasing the width of the second engaging claw  40 Ba 12 . Otherwise, the thickness of the second engaging claw  40 Ba 12  may be larger than that of the first engaging claw  40 Ba 11 . 
     Fourth Embodiment 
     A fourth embodiment of the present disclosure will be described referring to  FIG. 25  to  FIG. 31 . In the following description, the common configurations that have been described will be designated to the same reference signs and the duplicate description will be omitted. 
       FIG. 25  is a view showing a clip introduction device of a clip device according to the present embodiment. A clip device  100 M according to the present embodiment includes a clip unit (endoscopic treatment device)  1 M and a clip introduction device  200 M for operating the clip unit  1 M. The clip unit  1 M is used by being loaded in the clip introduction device  200 M. 
     The clip introduction device  200 M includes a sheath  200 , an operation wire  230 M, and an operation portion  240 . For example, the clip introduction device  200 M is inserted through the treatment device insertion channel of the endoscope and is combined with the endoscope to be used. Accordingly, the sheath  220  is formed to be enough long compared with the length of the treatment device insertion channel of the endoscope. The sheath  220  has the flexibility and is bent following the bending of the insertion portion of the endoscope. 
     The sheath  220  includes a distal end tip  221 , a distal side coil  222 , and a hand-side coil  224 , and the whole heath  220  is formed in an elongated tubular shape. The distal side coil  222  is disposed at the distal end side of the sheath  220 . The distal end tip  221  is disposed at the distal end portion of the distal side coil  222 . 
       FIG. 26  is a view showing the schematic configuration of the clip unit  1 M according to the present embodiment. The clip unit (endoscopic treatment device)  1 M includes a clip  2 M having a pair of arms  21 M being openable and closable, a pressing tube  3 M having a substantially tubular shape, and a connection member  4 M configured to connect the pair of arms  21 M and the operation wire  230 M. As shown in  FIG. 25  and  FIG. 26 , the operation wire  230 M is configured to operate the connection member  4 M, and the proximal end thereof is connected to the operation portion  240  of the clip introduction device  200 M, and the distal end thereof is connected to the connection member  4 M. 
       FIG. 27  is a perspective view showing the configuration of the arms of the clip unit  1 M. A tail  211 M of the arms  21 M (that is, the proximal end side of the arms  21 M) includes a snap-fit hole  213 M, and the distal end of the connection member  4 M is engaged with the snap-fit hole  213 M. The tail  211 M of the arms  21 M includes a slit  212 M communicating with the snap-fit hole  213 M, and the proximal end of the slit  212 M opens at the proximal end of the tail of the arms  21 M. The tail  211 M of the arms  21 M is elastically deformable, and when the connection member  4 M attempts to pass through the slit  212 M from the snap-fit hole  213 M, the tail  211 M of the arms  21 M is elastically deformed and the width of the slit  212 M is expanded such that the distal end of the engaged connection member  4 M is separated from the arms  21 M through the slit  212 M. 
     Of course, the shape and the configuration of the snap-fit hole  213 M is not limited to the above-described shape and configuration and may be other shape and configuration that is detachably engaged with the distal end of the connection member  4 M. 
     As shown in  FIG. 26 , the connection member  4 M is configured to engage with the pair of arms  21 M and to be advanceable and retractable inside the pressing tube  3 M, and the connection member  4 M forms an arrowhead portion  41 M extending at the distal end of the connection member  4 M. A pair of snap-fit protrusion portions  42 M are formed to protrude in the radial direction from the distal end thereof in the arrowhead portion  41 M. The snap-fit protrusion portions  42 M are engaged with the snap-fit hole  213 M by being fit in the radial direction of the pressing tube  3 M such that the arms  21 M and the connection member  4 M are movably connected. The snap-fit protrusion portions  42  and the snap-fit hole  213 M do not necessarily have to be paired, and may be at least one. 
     Furthermore, as shown in  FIG. 27 , in the tail  211 M of the arms  21 M, an arm-tail convex portion  215 M is further formed to protrude toward the direction intersecting with the thickness direction of the arms  21 M.  FIG. 28  is a view showing the situation in which the tail of the arms of the clip unit is engaged with the pressing tube. As shown in  FIG. 28 , when the arm-tail convex portion  215 M is positioned inside the pressing tube  3 M, the protrusion direction of the arm-tail convex portion  215 M extends to intersect with the longitudinal direction of the pressing tube  3 M. 
     As shown in  FIG. 28 , a step portion  38 M is formed on the inner wall of the pressing tube  3 M biasing to the proximal end side of the pressing tube  3 M, and when the pair of arms  21 M is closed, the arm-tail convex portion  215 M and the step portion  38 M are engaged with each other such that the arms  21 M are locked to the pressing tube  3 M. 
     According to the clip unit  1 M of the present embodiment, the operation portion  240  is operated to pull the operation wire  230  and move the connection member  4 M to the proximal end side such that the pair of arms  21 M are retracted in the pressing tube  3 M and the pair of arms  21 M enters the closed state. In the closed state, the arm-tail convex portion  215 M of the arms  21   m  are engaged with the step portion  30 M of the pressing tube  3 M such that the movement of the arms  21 M inside the pressing tube  3 M is restricted. When the operation wire  230  is further pulled, the tail  211 M of the arms  21 M receives the force due to the snap-fit protrusion portion  42 M provided in the connection member  4 M to be elastically deformed and the width of the slit  212 M is expanded, and the snap-fit protrusion portion  42 M is separated from the snap-fit hole  213 M. The arm-tail convex portion  215 M is engaged with the step portion  38 M of the pressing tube  3 M so as to realize the locking and the releasing of the clip  2 M. 
       FIG. 29  is a view showing the schematic configuration of another clip unit  1 M according to the fourth embodiment as a modification example. As shown in  FIG. 29 , the distal end of the connection member  4 M has the arrowhead portion  41 M, and the pair of snap-fit protrusion portions  42 M (in  FIG. 29 , only one side thereof is designated with the reference sign, and the reference sign to the other side is omitted) are formed to protrude in the radial direction from the arrowhead portion  41 M. The pair of arms  21 M are joined and fixed at the arm fixation portion  22 M. Furthermore, each of the pair of arms  21 M extends toward the proximal end side from the arm fixation portion  22 M to form an arm extension portion  218 M (in  FIG. 29 , only one side thereof is designated with the reference sign, and the reference sign to the other side is omitted). The snap-fit hole  213 M (in  FIG. 29 , only one side thereof is designated with the reference sign, and the reference sign to the other side is omitted) is provided in the tail of the arm extension portion  218 M, and the snap-fit protrusion portion  42 M and the snap-fit hole  213 M are engageable with each other due to the advancement and the retraction of the connection member  4 M. The shape and the configuration of the present snap-fit hole  213 M may be set to be the same with that of the above-described embodiment. In the arm fixation portion  22 M, an elastic protrusion portion  226 M is provided in the direction orthogonal to the longitudinal direction of the pressing tube  3 M, that is, in the direction from the arm fixation portion  22 M toward the inner circumferential surface of the pressing tube  3 M. A step portion  32 M is provided in the inner wall of the pressing tube  3 M biasing to the proximal end of the pressing tube  3 M, and the step portion  32 M is configured to lock the advancement and the retraction of the arms  21 M inside the pressing tube  3 M by engaging with the elastic protrusion portion  226 M. Although at least one elastic protrusion  226 M may be provided, it is preferable to provide the pair of elastic protrusions  226 M at positions being opposite to each other in the radial direction in order to securely lock the pair of arms  21 M in the holding tube  3 M. 
     In  FIG. 29 , the step portion  32 M is the hole penetrating the inner wall and the outer wall of the pressing tube  3 M; however, the step portion  32 M is not limited to the hole and may be the concave portion formed on the inner wall of the pressing tube  3 M without penetrating to the outer wall of the pressing tube  32 M. Similarly, the step portion  32 M may be the convex portion formed in the inner wall of the pressing tube  3 M. Furthermore, as shown in  FIG. 30 , the step portion  32 M may be a ring formed of the metal material disposed inside the pressing tube  3 M. 
       FIG. 30  is a perspective view showing the pressing tube  3 M of another clip unit  1 M according to the present embodiment.  FIG. 31  is a view showing the clip unit  1 M having the pressing tube  3 M as shown in  FIG. 30 . The pressing tube  3 M includes a pressing tube main body  30  formed in the tubular shape, an elastically deformable protrusion-depression wing  31  extending outwardly in the radial direction, and the step portion  32 M. The pressing tube main body  30  is formed by the injection molding using a material more flexible than that of the clip unit  1 M, for example, the thermoplastic resin having appropriate elasticity such as the PPA (polyphthalamide), the PA (polyamide), the PEEK (polyetheretherketone), the LCP (liquid crystal polymer) and the like. The pressing tube main body  30  may be formed of the metal material instead of the thermoplastic resin. 
     Furthermore, as shown in  FIG. 30 , the wing  31  is a pair of convex portions protruding from and depressing with respect to the outer circumferential surface of the pressing tube  3 M, and the above-described ring made of the metal material as the step portion  32 M is provided at the proximal end side of the protrusion-depression wing  31 . 
     According to the fourth embodiment of the present disclosure, the tails of the arms are directly connected with the clip introduction device and the internal space of the clip unit may be maximally utilized. 
     Fifth Embodiment 
     In  FIG. 32 , the clip unit includes the clip  10  and the pressing tube  31 . The pressing tube  31  is configured to at least accommodate the proximal end portion of the clip  10 . The proximal end of the pressing tube  31  is connected to the distal end of an insertion member  60  via the connection member  65 . The operation wire  62  is inserted through the inside passage of the insertion member  60 . The connection member  63 A is configured to connect the distal end of the operation wire  62  and the proximal end portion of the clip  10 . 
     As shown in  FIG. 32 , the clip  10  according to the present embodiment includes two of arms  12 ,  13 . The arms  12 ,  13  includes a first pin (intermediate member)  110  in the proximal end portion thereof, and the first pin  110  is configured to movably connect the two arms  12 ,  13 . The two arms  12 ,  13  further includes long grooves  121 ,  131  respectively for the second pin  120  to be inserted through. The second pin  120  inserted into the long grooves  121 ,  131  may be slided along the long grooves  121 ,  131 . The two ends of the second pin  120  are fixed to the pressing tube  31 . When the first pin  110  is moved forwardly and backwardly via the operation wire  62 , the second pin  120  slides along the long grooves  121 ,  131  and the two arms  12 ,  13  open and close such that the distal ends  12   a ,  13   a  grasp or release the target issues. 
     As shown in  FIG. 32  and  FIG. 33 , the pressing tube  31  is formed in a hollow tubular shape, and the pressing tube  31  has a distal-end opening  311  and a proximal-end opening  312 . Two tube wall grooves  313  being opposite to each other are provided on the tube wall of the pressing tube  31 , and when the two arms  12 ,  13  are opened, the two arms  12 ,  13  pass through the tube wall grooves  313 . In the pressing tube  31 , a pair of pin holes  313  to which the two ends of the second pin  120  are fixed are provided on the tube wall thereof. 
     As shown in  FIG. 32  and  FIG. 34 , the connection member  63 A according to the present embodiment includes a first connection member  63 Aa and a second connection member  63 Ab. The first connection member  63 Aa and the second connection member  63 Ab are connected to the two ends of the first pin  110  and come into contact with the two arms  12 ,  13  from the two sides, respectively. The first connection member  63 Aa and the second connection member  63 Ab may have the same shape and dimension. 
       FIG. 35  is a side view of the first connection member  63 Aa. The first connection member  63 Aa is integrally formed of an elongated metal plate material. As shown in  FIG. 35 , the first connection member  63 Aa includes a distal end portion  63 Aa 1 , a main body portion  63 Aa 2 , and a proximal end portion  63 Aa 3  from the distal end side. 
     The proximal end portion  63 Aa 3  of the first connection member  63 Aa is connected to the distal end of the operation wire  62 . The width of the proximal end portion  63 Aa 3  is smaller than the width of the distal end portion  63 Aa 1  and the main body portion  63 Aa 2 . 
     The distal end portion  63 Aa 1  of the first connection member  63 Aa is the first hook claw (engaging portion). Similarly, the distal end portion of the second connection member  63 Ab is the second hook claw (engaging portion). The first hook claw  63 Aa 4  and the second hook claw are formed in the C-shape and form the internal space for hooking the end portion of the first pin  110 , respectively. In other words, the first hook claw  63 Aa 4  and the second hook claw are configured to hook the two ends of the first pin  110 . At the time of separating the clip  10  and the connection member  63 A, the operation wire  62  is pulled toward the proximal end side such that the first hook claw  63 Aa 4  and the second hook claw receive the force to be deformed and the connection with the first pin  110  is released. 
     The two arms  12 ,  13  are interposed between the first hook claw  63 Aa 4  and the second hook claw. It is preferable that the first hook claw  63 Aa 4  and the second hook claw come into contact with the arms  12 ,  13  from the two sides so as to prevent the arms  12 ,  13  from moving in the axial direction of the first pin  110 . 
     As shown in  FIG. 35 , the contact portion  63 Aa 5  extends from the first hook claw  63 Aa 4  so as to increase the contact area with the arms. The contact portion  63 Aa 5  may be integrally formed with the first hook claw  63 Aa 4 , or the first hook claw  63 Aa 4  and the contact portion  63 Aa 5  may be formed individually and then joined together. 
     It is preferable that the width of the hook claw where the contact portion is formed is larger than the width of other portion of the connection member. For example, as shown in  FIG. 35 , the width W 1  of the first hook claw  63 Aa 4  where the contact portion  63 Aa 5  is larger than the width W 2  of the main body portion  63 Aa 2 . 
     The thickness of the contact portion  63 Aa 5  is the same with the thickness of the first hook claw  63 Aa 4 . Instead, as shown in  FIG. 36 , the thickness of the contact portion  63 Aa 5  may be larger than the thickness of the first hook claw  63 Aa 4 . In the connection member, the thickness of the first hook claw  63 Aa 4  where the contact portion  63 Aa 5  is formed may be larger than the thickness of other portions of the connection member, for example, may be larger than the thickness of the main body portion  63 Aa 2 . In the case in which the thickness of the first hook claw  63 Aa 4  is larger than the thickness of the main body portion  63 Aa 2 , and it is possible to maintain enough strength of the first hook claw  63 Aa 4 , the contact portion  63 Aa 5  may not be provided. 
     As shown in  FIG. 35 , the contact portion  63 Aa 5  is continuously formed. The contact portion  63 Aa 5  may be intermittently formed. In the case in which the contact portion  63 Aa 5  is intermittently formed, it is preferable that the contact portion  63 Aa 5  is formed at the region where the force received by the hook claw when pulled by the operation wire  62  is most concentrated so as to prevent the tearing in the hook claw. For example, as shown in  FIG. 37 , the contact portion  63 Aa 5  is formed at least in the region from the root of the hook claw to the distal end of the hook claw along the longitudinal direction of the connection member. For example, the plurality of contact portions that are intermittently formed may extend radially from the hook claw. 
     The second connection member is formed to have the contact portion that is same with the contact portion  63 Aa 5  of the first connection member, and the duplicate description is omitted. 
     The contact portion is formed in the first hook claw and the second claw to increase the contact area with the arms such that the swing between the hook claw and the arms can be prevented and the connection stability between the connection member and the arms is ensured. Particularly, the width of the hook claw where the contact portion is formed is larger than other portions of the connection member such that the rotation around the longitudinal axis of the connection member as the rotation center is effectively suppressed. 
     The contact portion is configured to increase the width or the thickness of the hook claw such that the strength of the hook claw is significantly increased. Accordingly, when the operation wire  62  is pulled toward the proximal end side for separating the clip and the connection member, the hook claw is separated from the first pin only due to the deformation of the hook claw such that the possibility of fracturing the hook claw is decreased. 
     In the case in which the contact portions are intermittently formed, the force necessary for making the hook claw to deform becomes small and the possibility of fracturing the hook claw is decreased. These forces have a trade-off relationship therebetween. 
     Fifth Embodiment 
     Compared with the fourth embodiment, the fifth embodiment is different in the structure of the two connection members. The distal end portion of the connection member according to the present embodiment it an engaging portion including two engaging claws being opposite to each other rather than the hook claws. 
     According to the fifth embodiment, the two connection members are the same such that the first connection member  63 B will be taken as an example to describe. 
     As shown in  FIG. 38 , the first connection member  63 B includes an engaging portion (that is, the distal end portion)  63 B 1 , a main body portion  63 B 6 , and a proximal end portion  63 B 7 . 
     The two engaging claws  63 B 2  configuring the engaging portion  63 B 1  form an accommodation portion  63 B 3  and a notch  63 B 4  between the two engaging claws  63 B 2 . The accommodation portion  63 B 3  is configured to accommodate the first pin  110 . The gap between the two engaging claws  63 B 2  in the notch  63 B 4  is smaller than the outer diameter of the first pin  110  such that it is possible to press the first pin  110  into the accommodation portion  63 B 3  via the notch  63 B 4 . Accordingly, it is possible to make the first pin  110  to be fit in the space between the two engaging claws  63 B 2 . In the state in which the first pin  110  is fit in the space between the two engaging claws  63 B 2 , when the first pin  110  is pulled from the space between the two engaging claws  63 B 2 , the two engaging claws  63 B 2  are elastically deformed and the first pin  110  is separated from the space between the two engaging claws  63 B 2 . 
     The connection member  63 B including the engaging portion  63 B 1  is a plate-shaped member, and the connection member  63 B is in contact with the arms  12 ,  13  from the two sides so as to prevent the arms  12 ,  13  from moving in the axial direction of the first pin  110 . When the clip  10  and the connection member  63 B are separated from each other, the operation wire  62  is pulled toward the proximal end side such that the two engaging claws receive the force to be deformed and the first pin  110  is separated from the accommodation portion  63 B 3  via the notch  63 B 4 , thus the connection between the connection member  63 B and the first pin  110  is released. 
     As shown in  FIG. 38 , the contact portion  63 B 5  extends from the edge portion of the engaging claw  63 B 2  to increase the contact area with the arms  12 ,  13 . The contact portion  63 B 5  may be integrally formed with the connection member  63 B, or the contact portion  63 B 5  and the connection member  63 B may be individually formed and then joined together. It is preferable that the width W 1  of the engaging portion  63 B 1  where the contact portion  63 B 5  is formed is larger than the width W 2  of the other portions of the connection member  63 B. 
     The thickness of the contact portion  63 B 5  may be the same with the thickness of the engaging claw  63 B 2 . Otherwise, as shown in  FIG. 39 , the thickness of the contact portion  63 B 5  may be larger than the thickness of the engaging claw  63 B 2 . In the connection member  63 B, the thickness of the engaging portion  63 B 1  where the contact portion  63 B 5  is formed may be larger than the thickness of other portions of the connection member  63 B. In the case in which the thickness of the engaging claw  63 B 2  is larger than the thickness of the main body portion  63 B 6  and it is possible to maintain enough strength of the engaging claw  63 B 2 , the contact portion  63 Aa 5  may not be provided. 
     As shown in  FIG. 38 , the contact portion  63 B 5  is continuously formed. However, the contact portion  63 B 5  may be intermittently formed. For example, the plurality of contact portions  63 B 5  that are intermittently formed may extend radially from the engaging claw  63 B 2 . 
     The second connection member is formed to have the contact portion that is same with the contact portion  63 B 5  of the first connection member, and the duplicate description is omitted. 
     Similar to the fourth embodiment, the contact portion is formed in the engaging portion to increase the contact area with the arms such that the swing between the hook claw and the arms can be prevented and the connection stability between the connection member and the arms is ensured. Particularly, the width of the engaging portion where the contact portion is formed is larger than other portions of the connection member such that the rotation around the longitudinal axis of the connection member as the rotation center is effectively suppressed. 
     The contact portion is configured to increase the width or the thickness of the engaging portion such that the strength of the engaging portion is significantly increased. Accordingly, when the operation wire  62  is pulled toward the proximal end side for separating the clip and the connection member, the engaging claw is separated from the first pin only due to the deformation of the engaging claw such that the possibility of fracturing the hook claw is decreased. 
     In the case in which the contact portions are intermittently formed, the force necessary for making the engaging claw to deform becomes small and the possibility of fracturing the engaging claw is further decreased. These forces have a trade-off relationship therebetween. 
     Although each preferred embodiment of the present invention has been described above together with each embodiment, the present invention is not limited to this embodiment and each embodiment. Configurations can be added, omitted, replaced, and other modifications without departing from the spirit of the present invention. 
     Further, the present invention is not limited by the above description and is limited only by the appended claims.