Abstract:
The endoscopic treatment instrument according to the present invention includes an insertion portion having a distal end and a proximal end, the distal end being inserted into a body; a treatment portion provided at the distal end of the insertion portion; and a control portion provided at the proximal end of the insertion portion. The treatment portion includes a pair of forceps members; a tip cover which support a pivot shaft that pivots at least one of the pair of forceps members openably and closably with respect to the other forceps member; a distal end holding portion that is fixed to the distal end of the insertion portion and in which the tip cover is held relatively movably toward the distal end of the insertion portion and toward the proximal end of the insertion portion; a distal end locking member that restrains a relative movement by locking the tip cover onto the distal end holding portion when the pair of forceps members is opened to grasp a specified object; and a distal end release member that is provided on an operational member by which the pair of forceps members is opened and closed and that releases an engagement made by the distal end locking member between the tip cover and the distal end holding portion at least when the pair of forceps members is closed.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a treatment instrument for an endoscope, and more particularly, to a retaining device placed and retained in the interior of a body and an applicator used to retain the retaining device therein.  
         [0003]     2. Description of the Related Art  
         [0004]     An abdominal operation in which a medical procedure is performed by largely incising the abdominal wall, a laparoscopic surgery in which a medical procedure is performed by approaching the abdominal cavities through an incision formed in the abdominal wall, or an endoscopic procedure in which a desired treatment is performed by inserting a flexible endoscope into the body through the mouth or the anus is conventionally known as a method for performing a medical procedure that deals with, for example, internal organs of the human body.  
         [0005]     In the medical procedures using these methods, bodily tissues are sutured, tightly bound, or ligated. A retaining device that is placed and retained in a body is often used when such a treatment is performed. This type of retaining device is attached to an applicator, and is retained in a desired region of the body by operating the applicator from the interior of the body.  
         [0006]     US Patent Application Publication No. 2003-0181924 A1 discloses an example of this type of retaining device and an applicator used to retain the retaining device (hereinafter, a “treatment instrument” is used as a general term for the retaining device and the applicator). The treatment instrument disclosed by this related art has the following structure. A detachable needle attached to a curved needle is inserted into bodily tissues, and then a hook sheath is moved toward the distal end of the instrument. Thereafter, the detachable needle is engaged by a casing engaged with the distal end. The hook sheath is then pulled toward the proximal end of the instrument, and the detachable needle is detached from the curved needle.  
       SUMMARY OF THE INVENTION  
       [0007]     It is an object of the present invention to provide an improved endoscopic treatment instrument having higher operability.  
         [0008]     The endoscopic treatment instrument according to a first aspect of the present invention includes an insertion portion having a distal end and a proximal end, the distal end being inserted into a body; a treatment portion provided at the distal end of the insertion portion; and a control portion provided at the proximal end of the insertion portion, and the treatment portion includes a pair of forceps members; a tip cover which supports a pivot shaft that pivots at least one of the pair of forceps members openably and closably with respect to the other forceps member; a distal end holding portion that is fixed to the distal end of the insertion portion and in which the tip cover is held relatively movably toward the distal end of the insertion portion and toward the proximal end of the insertion portion; a distal end locking member that restrains a relative movement by locking the tip cover onto the distal end holding portion when the pair of forceps members is opened to grasp a specified object; and a distal end release member that is provided on an operational member by which the pair of forceps members is opened and closed and that releases an engagement made by the distal end locking member between the tip cover and the distal end holding portion at least when the pair of forceps members is closed.  
         [0009]     The endoscopic treatment instrument according to a second aspect of the present invention includes a casing holding portion that is provided at a distal end of an insertion portion to be inserted into a body and that holds a casing connected to a tip member by a thread, the casing containing the tip member detachably attached to one of a pair of forceps members after being passed through a tissue in response to a closing motion of the pair of forceps members at least one of which is pivoted openably and closably with respect to the other forceps member; a casing locking member which engages the casing holding portion and the casing together; and a guide member that is provided at the tip cover and that controls an engagement state made by the casing locking member between the casing holding portion and the casing.  
         [0010]     The endoscopic treatment instrument according to a third aspect of the present invention includes a pair of forceps members; a tip cover which supports a pivot shaft that pivots at least one of the pair of forceps members openably and closably with respect to the other forceps member; a receiving portion that detachably holds a side of a distal end of an endoscope to be inserted into a body; and a regulating member that regulates a position of the distal end of the endoscope at a relative position with respect to the tip cover in order to restrict an amount of projection of the distal end of the endoscope with respect to the receiving portion.  
         [0011]     The endoscopic treatment instrument according to a fourth aspect of the present invention includes a first sheath and a second sheath to a distal end of each of which a treatment portion used to perform treatment is connected and to a proximal end of each of which a control portion that operates the treatment portion is connected; a first holder which bundles the first sheath and the second sheath together; a second holder which bundles the first sheath and the second sheath together and that is provided nearer to the distal end than the first holder; a first adjusting member that provides sliding friction to the second sheath with respect to the first holder; and a second adjusting member that provides smaller sliding friction than the first adjusting member to the first sheath with respect to the second holder.  
         [0012]     The retaining device according to a fifth aspect of the present invention includes a string member that has an end and an opposite end; a tip member that is connected to the end of the string member; a thread locking member provided at the string member; a casing that has a space where the tip member and the thread locking member are contained and in which a tip-member locking member that is engaged with the tip member is provided; and a hole that is formed in the casing and into which a device that releases locking of the tip member by the tip-member locking member can be inserted. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]      FIG. 1  is a view showing a schematic structure of a suture instrument which is an embodiment of an endoscope and an endoscopic treatment instrument;  
         [0014]      FIG. 2  is a view on arrow A in  FIG. 1 , showing a structure of a control portion;  
         [0015]      FIG. 3  is a partial sectional view showing a structure of an insertion portion;  
         [0016]      FIG. 4  is a view of a valving element along line B-B in  FIG. 1 ;  
         [0017]      FIG. 5  is a sectional view along line C-C in  FIG. 4 ;  
         [0018]      FIG. 6  is an enlarged view of a distal end of the suture instrument;  
         [0019]      FIG. 7  is a view on arrow D in  FIG. 6 ;  
         [0020]      FIG. 8  is a view on arrow E in  FIG. 6 ;  
         [0021]      FIG. 9  is a sectional view along line F-F in  FIG. 7 ;  
         [0022]      FIG. 10  is a sectional view obtained when a forceps member is opened;  
         [0023]      FIG. 11  is a view on arrow G in  FIG. 10 ;  
         [0024]      FIG. 12  is a sectional view showing a treatment instrument including a detachable needle, a casing, and a suture thread;  
         [0025]      FIG. 13  is a sectional view along line H-H in  FIG. 12 , showing a state in which the detachable needle has been locked;  
         [0026]      FIG. 14  is a view showing an example of a device for releasing the locking of the detachable needle;  
         [0027]      FIG. 15  is a sectional view along line I-I in  FIG. 13 ;  
         [0028]      FIG. 16  is a sectional view for illustrating a suture method, showing a state in which a forceps member has been opened toward an incision;  
         [0029]      FIG. 17  is a sectional view showing a state in which the forceps member has been closed so as to pinch tissues including the incision;  
         [0030]      FIG. 18  is a view showing one aspect of the control portion that can reliably perform a needle-inserting operation twice;  
         [0031]      FIG. 19  is a view showing another aspect of the control portion that can reliably perform a needle-inserting operation twice;  
         [0032]      FIG. 20  is a sectional view along line J-J in  FIG. 19 ;  
         [0033]      FIG. 21  is a sectional view along line K-K in  FIG. 20 ;  
         [0034]      FIG. 22  is a view showing a state in which a stopper releasing button has been pushed from the state in  FIG. 21 ;  
         [0035]      FIG. 23  is a sectional view showing a state in which the detachable needle has been inserted into the casing by pulling a tip cover and the forceps member;  
         [0036]      FIG. 24  is a view showing a state in which the detachable needle contained in the casing has been detached from a curved needle by returning the tip cover and the forceps member toward the distal end;  
         [0037]      FIG. 25  is a view showing a state in which the forceps member has been opened after detaching the detachable needle from the curved needle;  
         [0038]      FIG. 26  is a view showing a state in which the treatment instrument is retained while the incision has been sutured;  
         [0039]      FIG. 27  is a sectional view showing a distal claw portion formed integrally;  
         [0040]      FIG. 28  is a view showing a structure in which a distal-end supporting portion, a bridge portion, and a casing holding portion are formed integrally with each other;  
         [0041]      FIG. 29  is a view showing a distal end of a suture instrument according to another embodiment, in which a receiving portion is provided with a cut; and  
         [0042]      FIG. 30  is a view showing a receiving portion provided with a cut and a tapered surface. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0043]     Embodiments of the present invention will be hereinafter described in detail with reference to the accompanying drawings.  
         [0044]      FIG. 1  shows a suture instrument that is an example of an endoscopic treatment instrument. A suture instrument (applicator)  1  has a long insertion portion  3  extended from a control portion  2  that is operated by an operator. The insertion portion  3  is inserted in an overtube  6  together with an endoscope inserting part  5  of an endoscope  4 . The tip of the insertion portion  3  projects from the distal end of the overtube  6 . A treatment portion  7  is attached to the tip of the insertion portion  3 .  
         [0045]     As shown in  FIG. 2 , the control portion  2  has an elongated control body  10  that has a rigid shaft extending in an insertion direction. The insertion portion  3  extends from a distal end  10 A of the control body  10 . A finger-hook ring  11  is attached to the proximal end of the control body  10 . A slit  12  is provided along a length direction of the control body  10  on the side nearer to the distal end than the ring  11 . A forceps operating portion  13  and a hook operating portion  14 , in order from the side of the ring  11 , are attached to the slit  12  independently and slidably in the axial direction of the control body  10 . ABS (acrylonitrile butadiene styrene) resin, polycarbonate, polyacetal, polyphenylsulfone, polyphthalamide, or polyether ether ketone can be mentioned as a material of the control portion  2 . The instrument can be produced at low cost by making the control portion  2  of ABS resin, polycarbonate, or the like. Since slidability is increased by making the control portion  2  of polyacetal, a physical force required in operating the instrument can be reduced. Additionally, since excellent chemical resistance and excellent heat resistance can be obtained by making the control portion  2  of polyphenylsulfone, polyphthalamide, or polyether ether ketone, a change in quality caused by disinfection or sterilization becomes small.  
         [0046]     A forceps operating wire (a forceps operating member, a first wire)  15  is fixed to the forceps operating portion  13 . The forceps operating wire  15  is guided to the inside of the insertion portion  3  through the inside of the slit  12 . In the hook operating portion  14 , a pair of handles  16  extend from a side of a cylinder  14 A toward the proximal end, and a finger-hook ring  17  is formed integrally with the base of the handle  16 . The interval between the pair of handles  16  is large enough to allow the entry of the forceps operating portion  13 . The hook operating portion  14  can have a long stroke by pulling the ring  17  of the handle  16  beyond the forceps operating portion  13 . A hook operating wire (a hook operating member, a second wire)  18  is fixed to the hook operating portion  14 . The hook operating wire  18  is guided to the inside of the insertion portion  3  through the inside of the slit  12 . The number of the handles  16  may be one, or may be more than two.  
         [0047]     Each of the control body  10 , the forceps operating portion  13 , and the hook operating portion  14  is made out of a resinous molded article, and are produced by fixing integrally-molded members in a snap-fit manner. In more detail, the control body  10  is produced by bending a developed member and then fixing this by a snap-fit connection. An independently molded ring  11  is fitted to the proximal end of the control body  10 . Each of the forceps operating portion  13  and the hook operating portion  14  is produced by bending a developed member in such a way as to cover the control body  10  and then fixing this by a snap-fit connection.  
         [0048]     As shown in  FIG. 3 , the insertion portion  3  has a hook sheath  21  extending from the distal end of the control portion  2  and a forceps sheath  22 . The hook operating wire  18  is passed movably back and forth through the inside of the hook sheath  21 . The forceps operating wire  15  is passed movably back and forth through the inside of the forceps sheath  22 .  
         [0049]     A movement control portion (a first holder)  25  that is a constituent of the control portion  2  and a scope holder (a second holder)  26  are disposed at the path of the insertion portion  3 . The two sheaths  21  and  22  are bundled in parallel with each other by the movement control portion  25  and the scope holder  26 . The movement control portion  25  has through-holes  30  and  31  that are formed in parallel with each other and through which the two sheaths  21  and  22  pass, respectively. A first adjusting member  32  is inserted in the through-hole  30  for the hook sheath  21  in such a way that its end projects therefrom. In this embodiment, a screw is used as the first adjusting member  32 . The sliding friction of the hook sheath  21  is increased by tightening the first adjusting member  32  so as to come into contact with the hook sheath  21 . On the other hand, the forceps sheath  22  is fixed to the movement control portion  25  in a state of being inserted in the through-hole  31 .  
         [0050]     The scope holder  26  has a holder body  35  having through-holes  33  and  34  that are formed in parallel with each other and through which the two sheaths  21  and  22  pass, respectively. A cylindrical receiving portion  36  through which the endoscope inserting part  5  of the endoscope  4  passes from the holder body  35  is formed integrally therewith. The through-hole  34  is formed in the scope holder  26 . The forceps sheath  22  is inserted in the through-hole  34  movably back and forth. A second adjusting member  37  is disposed so as to come into contact with the forceps sheath  22 . In this embodiment, a screw is used as the second adjusting member  37 . The sliding friction of the forceps sheath  22  is increased by tightening the second adjusting member  37  so as to come into contact with the forceps sheath  22 . On the other hand, no adjusting member is disposed at the through-hole  33  of the hook sheath  21  so as to be movable back and forth.  
         [0051]     Both sheaths  21  and  22  proceed toward the scope holder  26  either by gripping the sheaths  21  and  22  exposed between the scope holder  26  and the movement control portion  25  or by advancing the movement control portion  25 . Since the endoscope  4  held by the scope holder  26  does not move, the treatment portion  7  attached to the distal ends of both sheaths  21  and  22  can be advanced toward the endoscope  4 .  
         [0052]     On the other hand, when an operator intends to advance only the hook sheath  21 , the hook sheath  21  is gripped to be advanced. At this time, the movement control portion  25  is not moved by the first adjusting member  32 . The reason is that the sliding friction in the movement control portion  25  of the hook sheath  21  is small, and the sliding friction caused by the second adjusting member  37  in the scope holder  26  of the forceps sheath  22  is great. Therefore, the hook sheath  11  slides with respect to the movement control portion  25 , and only the hook sheath  21  is advanced.  
         [0053]     Thus, the movement control portion  25  and the scope holder  26  make it possible to properly use the sheaths  21  and  22  so as to advance both of the sheaths  21  and  22  or advance only the hook sheath  21 . The sheaths  21  and  22  being operated can be more easily confirmed by making a difference in color between the hook sheath  21  and the coil sheath  22 , by making the surface of one of the sheaths  21  and  22  uneven, or by making a difference in outer diameter between the sheaths  21  and  22 , in order to help the operator to operate the instrument.  
         [0054]     The sliding friction caused by the first and second adjusting members  32  and  37  can be adjusted by an amount of tightening. According to another aspect, O rings may be used as the first and second adjusting members  32  and  37 . If so, the sliding friction can be changed by the width of the O ring.  
         [0055]     Each of the movement control portion  25  and the scope holder  26  is made out of a resinous molded article. The movement control portion  25  and the scope holder  26  are produced by fixing integrally-molded members with a snap-fit. In more detail, the movement control portion  25  and the scope holder  26  are produced according to the following way. The sheaths  21  and  22  are passed through grooves of developed members, which become the through-holes  30 ,  31 ,  33 , and  34 , and the first adjusting members  32  and  37  are inserted. Thereafter, the developed members are bent and fixed by a snap-fit connection.  
         [0056]     The hook sheath  21  is inserted in a coil sheath  41 . The forceps sheath  22  is inserted in a coil sheath  42 . The two coil sheaths  41  and  42  extend forwardly from the scope holder  26 . Each of the coil sheaths  41  and  42  is made out of a flat coil obtained by closely winding a flat metallic plate. From this structure, component cost can be reduced, and the number of assembling steps can be reduced, when compared to a conventional structure in which tubes are used. The outer surface of each of the hook sheath  21  and the forceps sheath  22  is covered with a heat-shrinkable tube made of low density polyethylene, high density polyethylene, or fluorine resin such as FEP or PFA, or the like. If the heat-shrinkable tube is made of low density polyethylene, the sliding friction with the coil sheaths  41  and  42  can be reduced, and, additionally, the heat-shrinkable tube can be produced at low cost. If the heat-shrinkable tube is made of high density polyethylene, the sliding friction can be reduced further. If the heat-shrinkable tube is made of fluorine resin such as FEP or PFA, a change in quality caused by disinfection or sterilization is slight, because the fluorine resin has small sliding friction and is superior in chemical resistance and heat resistance. The instrument can be operated with a small force by allowing each of the above examples to reduce sliding friction.  
         [0057]     As shown in  FIG. 1 , a valving element  50  which bundles the two coil sheaths  41  and  42  and the endoscope inserting part  5  of the endoscope  4  together and by which an airtight structure is formed between the valving element  50  and the overtube  6  is disposed midway on the insertion portion  3 . Silicone rubber, natural rubber, or isopropylene rubber, or the like can be mentioned as a material of the valving element  50 . The valving element  50  is fixed to the coil sheaths  41  and  42 , for example, with an adhesive. As shown in  FIG. 4  and  FIG. 5 , the valving element  50  has through-holes  51  and  52  for the sheaths  41  and  42  and a through-hole  53  for the endoscope  4  that are formed in parallel with each other. The valving element  50  has tapered surfaces  54  and  55  formed by slantingly cutting both end surfaces of a cylindrical member. The length in the insertion direction of a part  52 A on the opposite side of the through-hole  52  is shortened by the tapered surfaces  54  and  55 . A press-fit part  56 , whose outer shape is a substantially circular arc when viewed cross-sectionally, is formed on the outer periphery of the valving element  50 . A press-fit part  57  having the same shape as the press-fit part  56  is formed on the inner periphery of the through-hole  53  used for the endoscope  4 . Since the tapered surfaces  54  and  55  are provided, the valving element  50  is not easily caught by the overtube  6 . Since the press-fit part  56  is further provided, the valving element  50  comes into contact with the overtube  6  at only one place in the insertion direction. Therefore, from a decrease in contact area, the sliding friction is expected to be reduced, and it becomes easy to insert the endoscope inserting part  5 . Likewise, since the press-fit part  57  makes a contact area with the endoscope inserting part  5  small, it becomes easy to insert the endoscope inserting part  5 . Additionally, since the rigidity is improved by making a part  55 A thick, the valving element  50  can be prevented from being deformed. Since the opening of each of the through-holes  51  to  53  is tapered to enlarge the outer diameter, the coil sheaths  41  and  42  and the endoscope inserting part  5  can be easily inserted.  
         [0058]     Next, the treatment portion  7  will be described.  
         [0059]     As shown in  FIG. 6  to  FIG. 8 , a receiving portion  60  is fixed to the distal end of the insertion portion  3 . As shown in  FIG. 8 , the receiving portion  60  has a C-shaped base  61  into which the endoscope inserting part  5  of the endoscope  4  can be inserted. Since a part of the base  61  is cut off, an outer shape obtained by combining the endoscope inserting part  5  and the suture instrument  1  together becomes small, and the diameter of the overtube  6  can be reduced. Additionally, a contact area between the receiving portion  60  and the overtube  6  can be reduced. From these, the insertion into the overtube  6  or into body cavities can be easily performed. To secure the connection strength between the base  61  and the endoscope  4 , a flexible member  62  is affixed to the inner side of the base  61 . The flexible member  62  additionally has a function to prevent the base  61  from damaging the endoscope  4 .  
         [0060]     As shown in  FIG. 6  and  FIG. 7 , in the receiving portion  60 , a taper portion  63  is formed at the proximal end toward which the coil sheaths  41  and  42  are pulled in. The taper portion  63  is formed to reduce the outer diameter of the receiving portion  60  toward the proximal end. As a result, the outer periphery of the base  61  is not caught by the taper portion  63  when the treatment portion  7  drawn out from the overtube  6  is again contained in the overtube  6  during manipulation.  
         [0061]     As shown in  FIG. 9 , a cylindrical hole  71 A to which the distal end of the coil sheath  42  is fixed on the outer periphery thereof is disposed in the receiving portion  60 . A distal-end supporting member  71  is disposed movably back and forth in a hole  71 B. The distal-end supporting member  71  extends along the axial line of the coil sheath  42 . The forceps sheath  22  is fixed to the proximal end thereof, and the forceps operating wire  15  is passed through the inside thereof.  
         [0062]     A hole  72  and a slit  73  are formed in the distal end of the distal-end supporting portion  71 . The hole  72  and the slit  73  are formed on the straight line of the distal-end supporting portion  71 , and an end of the slit  73  extends nearer to the proximal end than the hole  72 . A pin  75  that is a first locking member (a distal-end locking member) is inserted in the hole  72 . A part of the pin  75  projects into the distal-end supporting portion  71  in a state in which the pin  75  is inserted in the hole  72 . The pin  75  is attached to the outer periphery of the distal-end supporting portion  71  by a leaf spring  76  serving as an urging member. The leaf spring  76  is urged in a direction in which the pin  75  is contained in the hole  72 . On the other hand, an elongated release member  77  is inserted in the slit  73 . The release member  77  is a second release member (a forceps release member) fixed to the distal-end supporting portion  71  by, for example, laser welding or by an adhesive. A proximal end of an elongated plate member and the distal-end supporting portion  71  in the direction of the center axis are slantingly cut.  
         [0063]     A tube part  81  of a tip cover  80  is inserted in the distal-end supporting portion  71  from the side of the distal opening. The tip cover  80  has the tube part  81  that has the outer diameter substantially equal to the inner diameter of the distal-end supporting portion  71  and a cover body  82  formed integrally at the tip of the tube part  81 . A coiled spring  83  is disposed outside the tube part  81 . An urging force is applied so as to separate the cover body  82  from a bridge portion  85  fixed to the distal opening of the distal-end supporting portion  71 . The bridge portion  85  extends in a direction perpendicular to the insertion direction. The tip of the distal-end supporting portion  71  is fixed to an end of the bridge portion  85 , and the proximal end of a cartridge supporting member  86  described later is fixed to an opposite end of the bridge portion  85 .  
         [0064]     A plurality of slits  91 ,  92 , and  93  are formed in the tube part  81  in the length direction. The slit  91  is formed according to the position at which the hole  72  of the distal-end supporting portion  71  is formed around the axial line of the tube part  81 . The slit  91  has a width so as not to allow entry of the pin  75 . However, only a base  91 A of the slit  91  is increased in width, so that the tip of the pin  75  can enter the slit  91 . The slit  92  is formed according to the position at which the slit  73  of the distal-end supporting portion  71  is formed around the axial line. The slit  92  has a width large enough to insert the release member  77 . The base of the slit  92  extends nearer to the proximal end than the base  91 A of the slit  91 .  
         [0065]     As shown in  FIG. 6 , the slit  93  is formed at a position where the other slits  91  and  92  are avoided. A pin  95  fixed to the bridge portion  85  is inserted in the slit  93  so as to be used as a slide guide of the tube part  81 .  
         [0066]     As shown in  FIG. 9 , a rod  100  that is a constituent of an opening and closing mechanism is inserted in the tube part  81  movably back and forth. The forceps operating wire  15  is fixed to the proximal end of the rod  100 . A concave portion  101  extending in the radial direction is formed at a position near to the proximal end of the rod  100 . A ball  102  serving as a second locking member (a forceps locking member) is inserted in the concave portion  101 . The ball  102  is urged by a coiled spring  103  outwardly in the radial direction. The ball  102  can enter a large-diameter part  92 A provided on the base of the slit  92  of the tube part  81 , but cannot enter a more forward part than the large-diameter part  92 A.  
         [0067]     A release member  105  serving as a first release member (a distal-end release member) is provided at a position that is occupied more forwardly than the ball  102  and that is obtained by the rotation around the axial line by 180 degrees. The release member  105  projects at a position where the release member  105  coincides with the ball  102  around the rotational axis. The base of the release member  105  has a tapered surface by which the pin  75  can easily ride.  
         [0068]     An end of each of two link members  111  and  112  is rotatably attached to the tip of the rod  100  via a pin  110 . An opposite end of the link member  111  is rotatably attached to an end  115 A of a forceps member  115  via a pin  113 . The forceps member  115  has a bent part  115 C between the end  115 A of the forceps member  115  and an opposite end  115 B thereof. The bent part  115 C is rotatably pivoted on the tip cover  80  by means of a pin (pivot shaft)  116 . A curved needle (attaching portion)  120  is fixed to the opposite end  115 B of the forceps member  115 . A detachable needle  121  is detachably attached to the tip of the curved needle  120 . The detachable needle  121  has the pointed end part, a diameter-reduced contracted part  122  next to the pointed end part, and then a proximal end part  123 . The proximal end part  123  is fitted to the curved needle  120 . An end of a suture thread  125  is drawn in the proximal end part  123 , and is fixed there. The contracted part  122  is formed when the suture thread  125  inserted therein is fixed while caulking concave parts formed on the detachable needle  121  from the four directions. According to this structure, the outer diameter of the detachable needle can be made smaller than a conventional detachable needle to which a suture thread is fixed by use of the knot of the suture thread. The suture thread  125  is drawn out through a slit  120 A of the curved needle  120 .  
         [0069]     On the other hand, the opposite end of the other link member  112  is rotatably connected to the proximal end of an intermediate member  131 A by means of a pin  130 . The distal end of the intermediate member  131 A is rotatably supported by the tip cover  80  via a pin  132 . A forceps member  131  is rotatably pivoted on the tip cover  80  by means of the pin (pivot shaft)  132  on the side of the proximal end. A tip part  131 B of the forceps member  131  is shaped like a ring having an opening  133 , and is curved forwardly. A needle  134  that is inserted into tissues is fixed to the forefront of the forceps member  131 .  
         [0070]     As shown in  FIG. 10 , when the pair of forceps members  115  and  131  is opened, the tip of the detachable needle  121  attached to the curved needle  120  and the tip of the needle  134  of the forceps member  131  coincide with each other in the insertion direction. Since the needles  121  and  134  are inserted into tissues substantially simultaneously, the needles  121  and  134  do not easily come off from the tissues, and can be reliably inserted thereinto. Additionally, the needles  121  and  134  can be inserted deep thereinto.  
         [0071]     As shown in  FIG. 6 , in the forceps member  131 , a part  131 C supported by the tip cover  80  via the pin  132  is disposed outside the tip cover  80 . The tip cover  80  has a concave part  80 B, and the part  131 C of the forceps member  131  is supported by the concave portion  80 B via the pin  1321 . As shown in  FIG. 7 , a large difference in level does not exist at the boundary between the part  131 C of the forceps member  131  and the tip cover  80 , and hence the endoscope can be easily inserted into the body cavities, and the operability is improved.  
         [0072]     Additionally, since the forceps member  131  is supported outside the tip cover  80 , a space used to dispose a charging spring that urges the forceps member  131  so as to be reliably closed is secured in the tip cover  80 . As shown in  FIG. 7  and  FIG. 9 , a charging spring  140  is wound like a coil with the pin  132  provided with a clearance. When the pair of forceps members  115  and  134  is closed, an end  140 A of the charging spring  140  comes into contact with the proximal end of the intermediate member  131 A. An opposite end  140 B of the charging spring  140  comes into contact with the part  131 C of the forceps member  131 . When the pair of forceps members  115  and  131  is closed, the charging spring  140  applies an urging force so as to completely close the opposite end  131 B of the forceps member  131 .  
         [0073]     Since the charging spring  140  is wound like a coil, both of the ends  140 A and  140 B extend toward mutually different positions in the width direction. As shown in  FIG. 11 , the end  140 A is disposed outside, whereas the opposite end  140 B is disposed near the center.  FIG. 11  shows a state in which the pair of forceps members  115  and  131  has been opened, and the charging spring  140  does not function. An opposite end  112 A of the intermediate member  131 A is expanded outwardly in the width direction so as to come into contact with the end  140 A of the charging spring  140 . On the other hand, the inside of the opposite end  112 A of the intermediate member  131 A is cut off, and the opposite end  112 A thereof is deformed in the width direction. Since the opposite end  112 A of the intermediate member  131 A is structured in this way, interference between the intermediate member  131 A and a casing  150  can be prevented when the casing  150  is moved back and forth. Additionally, in the structure to avoid the casing  150 , adequate rigidity can be obtained by forming the deformed structure.  
         [0074]     As shown in  FIG. 6 , the forceps members  115  and  131  are provided with projecting stoppers  151  and  152 , respectively, that come into contact with a tip surface  80 A of the tip cover  80  when the pair of forceps members  115  and  131  is completely closed. Since the stoppers  151  and  152  come into contact therewith, the forceps member  115  does not sag, and the axial line of the detachable needle  121  is not easily deviated when the pair of forceps members  115  and  131  is closed.  
         [0075]     Next, a description will be given of the casing  150  into which the opposite end of the suture thread  125  is drawn as shown in  FIG. 9  and the casing supporting portion  86  that supports the casing  150 .  
         [0076]     As shown in  FIG. 12  and  FIG. 13 , the casing  150 , the suture thread (string member)  125 , and the detachable needle (tip member)  121  constitute a cartridge (also called a “retaining device”)  153  that is retained in the body.  
         [0077]     The casing  150  is formed by combining cylindrical members  161  and  162  together, and has a reception hole  163  into which the detachable needle  121  can be inserted. The distal end side of the reception hole  163  has a tapered surface  163 A by which the axial line of the reception hole  163  and the axial line of the detachable needle  121  are allowed to easily coincide with each other. A wire spring  165 , which is a needle locking member (tip-member locking member) used to prevent the detachable needle  121  from falling off, is inserted in the reception hole  163 . The wire spring  165  is formed by bending a rod like the letter U and bending both ends  166  of the wire spring  165  by 90 degrees so as to become parallel in the same direction. The ends  166  of the wire spring  165  are disposed to reduce the width of the reception hole  163 . In an initial state, the ends  166  of the wire spring  165  are contained in a groove  167  the width of which is greater than that of the reception hole  163 . When the detachable needle  121  enters the reception hole  163 , both ends  166  can be expanded. As shown in  FIG. 13 , when the detachable needle  121  is contained in the reception hole  163 , the proximal end part  123  of the detachable needle  121  is completely contained in the casing  150 . Therefore, tissues are never damaged by the proximal end part  123  of the detachable needle  121 .  
         [0078]     Polyphenylsulfone, polyphthalamide, polyether ether ketone, titanium alloy, or pure titanium can be mentioned as a material of the casing  150 . If the casing  150  is made of polyphenylsulfone, polyphthalamide, or polyether ether ketone, the casing  150  does not easily undergo a change in quality in the living body, because they are superior in chemical resistance and acid resistance. Since these materials are also superior in welding, an assembling operation can be performed by use of ultrasonic wave welding or laser welding. Pure titanium or titanium alloy is superior in biocompatibility.  
         [0079]     When the detachable needle  121  is contained in the casing  150 , the wire spring  165  pinches the contracted part  122  of the detachable needle  121 . If an operator intends to pull out the detachable needle  121  from the casing  150 , the wire spring  165  is moved and slid together therewith, and the end  166  enters a narrow part  168  (see  FIG. 12 ) on the distal-end side. Since the end  166  cannot be opened here, the wire spring  165  serves as a stopper, and prevents the detachable needle  121  from falling off. If the operator intends to pull out the detachable needle  121  from the casing  160 , it is recommended to insert a release device into a release hole  170  formed in the side of the casing  160  and then return the wire spring  165  to the proximal end side as shown by the arrow in  FIG. 13 . As a result, the end  166  returns to the groove  167 , whereby both ends  166  can be opened while being pushed. Therefore, the detachable needle  121  can be pulled out from the casing  160  by pulling the detachable needle  121  in a state of fixing the position of the wire spring  165 .  
         [0080]     For example, a device having a structure in which a holding member  181  of a forceps  180  is provided with a release pin  182  can be mentioned as the release device as shown in  FIG. 14 . If the operator inserts the release pin  182  through the release hole  170  by operating the instrument from the proximal end thereof, the detachable needle  121  can be pulled out from the casing  150  even during the manipulation. The form of the release device is not limited to that in  FIG. 14 . Any type of device can be employed as long as the device can be inserted through the release hole  170 , and the wire spring  165  can be moved toward the proximal end side.  
         [0081]     As shown in  FIG. 12  and  FIG. 15 , the suture thread  125  drawn into the casing  150  is pulled into the reception hole  163  from a position nearer to the proximal end than an area that the detachable needle  121  enters on the midway of the reception hole  163 . The proximal end of the reception hole  163  leads to a large-diameter hole  190  formed in the surface of the proximal end of the casing  150 . A brake portion (thread locking member)  191  is disposed inside the hole  190 . The brake portion  191  has a flat shape obtained by winding a metallic plate  193  around an elastic member  192  through which the suture thread  125  is passed and then flattening the metallic plate  193 . Predetermined sliding friction is generated between the suture thread  125  and the brake portion  191 . The casing  150  has a slit  194  passing through the casing  150  in the radial direction. The brake portion  191  is loosely fitted to the slit  194 . Since a step  195  formed between the hole  190  and the slit  194  functions as a stopper of the brake portion  191 , the brake portion  191  never projects out of the casing  150  even when the brake portion  191  is pulled in the length direction of the suture thread  125 . The brake portion  191  makes it possible to generate predetermined sliding friction when the casing  150  is moved between an end of the suture thread  125  and the opposite end thereof, and, as a result, the movement of the casing  150  is restrained.  
         [0082]     Herein, the end of the suture thread  125  pulled out from the surface of the proximal end of the casing  150  forms a loop (hook catching portion)  200 . A double, drawn-untied knot  201  is employed to form the loop  200 . Since the double, drawn-untied knot  201  can make a knot of the loop  200  small, the loop  200  can be easily inserted into the hook sheath  21  even if the inner diameter of the hook sheath  21  is small.  
         [0083]     As shown in  FIG. 10 , the casing  150  is contained in the casing supporting member  86 . A ball (a third locking member, a casing locking member)  205  that is inserted through the hole  203  of the casing supporting member  86  is engaged with each annular concave portion  202  formed on the side of the casing  150 . The ball  205  is urged to be fastened to the casing  150  by a leaf spring  206  serving as an urging member fixed to the casing supporting member  86 . It is permissible to unite the ball  205  and the leaf spring  206  together by use of laser welding or an adhesive. The end of the casing supporting member  86  is inserted movably back and forth in a guide hole  210  used as a guide member of the tip cover  80 . The guide hole  210  has its proximal end whose diameter has been increased. The ball  205  can be moved outwardly in the radial direction in a part  210 A widened as shown in  FIG. 9 . A distal end part  210 B is smaller in the diameter of the guide hole  210  than the diameter-increased part  210 A, and hence the ball  205  cannot be moved outwardly in the radial direction.  
         [0084]     In the casing supporting member  86 , a distal claw portion  211  attached to the hook sheath  21  is fitted into the hole  190  of the casing  150 . The distal claw portion  211  has a flange  211 A that serves as a stopper by coming into contact, from the distal end side, with a step  86 A formed on the inner periphery of the casing supporting member  86 . A hook  212  is contained in the through-hole thereof. The hook  212  is fixed to the tip of the hook operating wire  18  passed movably back and forth through the hook sheath  21 . The loop  200  (see  FIG. 12 ) formed on the opposite end of the suture thread  125  is caught by the hook  212 . Conventionally, an inner tube has been provided between the hook sheath  21  and the casing supporting portion  86 . However, in this embodiment, the structure of the instrument is simplified by excluding the inner tube. As a result, component cost can be reduced, and the number of assembling steps can be reduced.  
         [0085]     As shown in  FIG. 7 , a mark  220 , which is used as a restriction part by which the endoscope  4  is positioned in the insertion direction, is provided on the side of the tip cover  80  of the treatment portion  7 . A rigid part of the distal end of the endoscope  4  and a rigid part of the treatment portion  7  can be overlapped with each other in the insertion direction by putting the distal end of the endoscope  4  onto the mark  220 . Conventionally, the distal end of the endoscope  4  has been positioned on the receiving portion  60 , and hence the whole length of the rigid part is equal to the sum of the length of the treatment portion  7  and the length of the rigid part of the endoscope  4 . Therefore, disadvantageously, it has been difficult to achieve excellent insertability into the overtube  6  or into the living body. However, in this embodiment, the length of the rigid part is shortened, and hence insertability is improved. Additionally, since the endoscope  4  is disposed nearer to the distal end, the tip cover  80  or the other elements do not block the visual field of an observation device of the endoscope  4 . Therefore, a sufficient visual field can be obtained. A plate member  221  caused to abut against the surface of the end of the endoscope  4  may be used as a restricting member instead of the mark  220 , and may be protruded from the tip cover  80  as shown by the broken line in  FIG. 7 . Additionally, as shown in  FIG. 8 , an inclined surface  225  is formed by slantingly cutting the corner of the tip cover  80 . The inclined surface  225  makes it possible to facilitate a back-and-forth operation, because the suture instrument  1  is contained within the inner diameter of the overtube  6  shown by the phantom line in  FIG. 8 .  
         [0086]     Next, the operation of this embodiment will be described. Although the following description is concerned with a case in which an incision formed in a stomach wall is sutured, a target region is not limited to the stomach wall. Hollow organs, such as the esophagus, duodenum, small intestine, large intestine, womb, or bladder may be targeted. Additionally, a natural opening through which the endoscope  4  is inserted is not limited to the mouth. The nose or anus may be used as the natural opening. Additionally, the treatment instrument of the present invention may be used to suture a mucous-membrane defective part or a perforated part generated by hemostasis or an ulcer.  
         [0087]     The endoscope inserting part  5  of the endoscope  4  is passed through the scope holder  26 , the valving element  50 , and the receiving portion  60  in this order, and then the surface of the end of the endoscope  4  is allowed to coincide with the mark  220 . To firmly fix the endoscope  4  to the suture instrument  1 , the end of the endoscope  4  and the receiving portion  60  may be fastened together by, for example, a tape. Thereafter, the cartridge  153  is set at a desired position of the suture instrument  1 . The overtube  6  is inserted from the mouth of a patient to the neighborhood of the cardiac orifice of the stomach or into the stomach by use of another endoscope. Thereafter, the suture instrument  1  fixed to the endoscope  4  via the overtube  6  is inserted into the stomach.  
         [0088]     In the interior of the stomach, the position of the incision of a tissue that is a target region is confirmed by an observation device of the endoscope  4 . Since the end of the endoscope  4  is disposed nearer to the distal end of the suture instrument than a conventional endoscope, the visual field is not easily blocked by the suture instrument  1 , so that the incision of the tissue and the detachable needle  121  can come within the same visual field.  
         [0089]     Thereafter, the pair of forceps members  115  and  131  is opened in the interior of the stomach before suturing. In more detail, an operator advances the forceps operating portion  13  of the control portion  2 . The forceps operating wire  15  is then advanced, and the link members  111  and  112  connected to the rod  100  allow the forceps members  115  and  131  to pivot on the pins  106  and  132  and be opened. As shown in  FIG. 16 , when the thus opened forceps members  115  and  131  are allowed to approach the incision SO that is a target region, the pair of forceps members  115  and  131  is closed in such a way as to pinch tissues around the incision SO with the forceps members  115  and  131 .  
         [0090]     When the operator allows the forceps operating portion  13  of the control portion  2  to recede therefrom, the forceps operating wire  15  recedes, and the link members  111  and  112  are pulled into the tip cover  80 , so that the forceps members  115  and  131  pivot on the pins  106  and  132 , respectively, and are closed. The needle  134  of the forceps member  131  is then inserted into the tissue, and presses the tissue against the incision SO. On the other hand, the curved needle  120  of the forceps member  115  is inserted into a tissue on the opposite side of the forceps member  131  with the incision SO therebetween, and is protruded toward the casing  150  through the tissue drawn in by the forceps member  131  across the incision SO. As a result, as shown in  FIG. 17 , the curved needle  120  and the suture thread  125  are passed through the incision SO.  
         [0091]     If the incision SO is relatively large and cannot be pinched by a single suturing operation, it is permissible to first make a puncture in an end of the incision SO, then make a gap between the detachable needle  121  and the needle  134  by widening the curved needle  120  to the extent of about a half, then take a tissue on the opposite side of the incision SO into the gap, and perform a suturing operation while inserting the needle there.  
         [0092]     If the tissue is hard at this time, the detachable needle  121  cannot be easily inserted through the tissue, and the forceps operating portion  13  cannot be stopped at a position at which the detachable needle  121  arrives through the tissue, because a large force is applied onto the forceps operating portion  13 . Accordingly, the detachable needle  121  is often moved, as a serial operation, to a position at which the detachable needle  121  is engaged with the casing  150 . If so, the incision cannot be sutured by a twice-inserting operation as described above. To reliably perform the twice-inserting operation, it is recommended to structure the control portion  2  as shown in  FIG. 18 . In the control portion  2 , a hole  401  leading to the slit  12  is formed in the proximal end of the control body  10 , and a cam rod  402  extended to the end of the ring  11  is inserted in the hole  401 . An abutment portion  403  is disposed at the end of the hole  401  in such a way as to reduce the opening diameter. A spiral cam groove  405  is formed on the inner periphery of the hole  401 . The cam groove  405  extends in the circumferential direction with a length greater than at least a semicircle (180 degrees). Further, a rod  406  that can pass through the abutment portion  403  extends from the cam rod  402  toward the distal end. The rod  406  is inside the slit  12 , and a stopper  407  is disposed at the tip of the rod  406  so that the stopper  407  can come into contact with the forceps operating portion  13 . Further, on the outer periphery of the cam rod  402 , a pin  408  extends outwardly in the radial direction. The pin  408  is inserted in the cam groove  405 , and the ring  11  is engaged with the control body  10  with the pin  408  therebetween.  
         [0093]     In the control portion  2 , the forceps operating portion  13  can be pulled until the forceps operating portion  13  comes into contact with the stopper  407 . When the ring  11  is rotated from the position shown in  FIG. 18  by 180 degrees, the rotational motion of the pin  408  rotating together with the ring  11  is transformed into the linear motion of the ring  11  by the cam groove  405 , so that the ring  11  recedes. The stopper  407  formed integrally with the ring  11  recedes by, for example, a movement amount X. Since the stopper  407  recedes, the forceps operating portion  13  can further recede by the movement amount X. If the position obtained at this time is set as a position to which the tip cover  80  is moved until the detachable needle  121  is engaged with the casing  150 , and if the first position of the stopper  407  is set as a first position for a twice-inserting operation, the twice-inserting operation will be reliably performed.  
         [0094]     Another aspect is shown in FIG. B. As shown in  FIG. 19 , an obstacle rail  410  is disposed with a predetermined length in the length direction on the inner surface of the slit  12  of the control body  10  so as to have a ridge toward the inside of the slit  12 . A forceps operating portion  411  is attached to the slit  12  slidably back and forth. The forceps operating portion  411  is a slider by which the pair of forceps members  115  and  131  is opened or closed. As shown in  FIG. 20 , a hole  421  perpendicular in the sliding direction is provided inside. A stopper member  412  is inserted in the hole  421 . The stopper member  412  is urged by a coiled spring  414 , which is an elastic member, toward an opening narrowed in the hole  412 . The end of the stopper member  412  projects from the forceps operating portion  411 , and is used as a stopper releasing button  415 . The stopper member  412  has a cut  416  formed in the side thereof. As shown in  FIG. 21 , the cut  412  is sufficiently larger than the obstacle rail  410 . However, since the position of the cut  416  does not coincide with the position of the obstacle rail  410  in a natural state, the forceps operating portion  411  can recede only until a stopper  413  comes into contact with the obstacle rail  410 . As shown in  FIG. 22 , when the stopper releasing button  415  is pushed, the stopper  413  is moved in proportion to the shrinkage of the coiled spring  414 , and the position of the cut  416  coincides with the position of the obstacle rail  410 . Since it becomes possible to avoid the obstacle rail  410  by means of the cut  416 , the forceps operating portion  411  can be allowed to further recede toward the ring  11 . The movement amount of the forceps operating portion  411  can be controlled by allowing the operator to push the stopper releasing button  415  provided at the end of the stopper  413  as described above, and hence the twice-inserting operation can be reliably performed.  
         [0095]     When the curved needle  120  and the suture thread  125  are passed through the incision SO, the forceps member  131  is urged by the urging force of the charging spring  140  in the closing direction, and the needle  134  firmly bites into the tissue. Further, the stoppers  151  and  152  of the forceps members  115  and  131  are pushed against the tip surface  80 A of the tip cover  80 . As a result, the forceps members  115  and  131  are prevented from sagging, and the axial line of the detachable needle  121  and the axial line of the casing  150  substantially coincide with each other.  
         [0096]     When the pair of forceps members  115  and  131  is completely closed, or immediately before the pair of forceps members  115  and  131  is completely closed, the tapered surface of the release member  105  of the rod  100  pulled into the tube part  81  of the tip cover  80  pushes the pin  75  up. The engagement between the tube part  81  and the distal-end supporting portion  71  is released by pushing the pin  75  up. As a result, the tip cover  80  can be pulled into the distal-end supporting portion  71 . Therefore, when the forceps operating wire  15  is allowed to further recede as shown in  FIG. 23 , the tip cover  80  recedes while compressing the coiled spring  83 , and the forceps members  115  and  131 , which are connected to the tip cover  80  by means of the pins  116  and  132  and the stoppers  151  and  152 , recede. At this time, the ball  102  of the tube part  81  enters the large-diameter part  92 A beyond the release member  77 , and the tube part  81  and the rod  100  are connected together.  
         [0097]     On the other hand, the casing  150  is held by the casing supporting member  86 , and is not moved. Moreover, the outer periphery of the ball  205  engaged with the casing  150  is covered with the small-diameter part  210 B of the guide hole  210  by allowing the tip cover  80  to recede, and hence the ball  205  cannot be moved outwardly in the radial direction. As a result, in a state of preventing the movement of the casing  150 , the detachable needle  121  attached to the tip of the curved needle  120  is inserted in the casing  150 . In the reception hole  163 , the detachable needle  121  is locked to the casing  150  by the wire spring  165 .  
         [0098]     When the forceps operating wire  15  is completely pulled, the forceps operating portion  13  is advanced. The tip cover  80  starts moving to the original position by the restoring force of the coiled spring  83  disposed outside the tube part  81 . At this time, the tip cover  80  and the rod  100  are advanced together since the tube part  81  and the rod  100  are connected together by means of the ball  102  entering the large-diameter part  92 A of the slit  92 . Therefore, the pair of forceps members  115  and  131  is advanced without being opened, and the curved needle  120  attached to the forceps member  115  makes a parallel movement so as to recede from the casing  150 .  
         [0099]     The detachable needle is disengaged from the curved needle  120  by this parallel movement. As shown in  FIG. 24 , the detachable needle  121  stays while being contained in the casing  150 , and the curved needle  120  recedes from the casing  150 . Since the pair of forceps members  115  and  131  has not yet opened at this time, interference never occurs between the curved needle  120  and the casing  150 . Thereafter, the ball  102  proceeding together with the tube part  81  of the tip cover  80  is brought into contact with the release member  77 , and is pushed into the rod  100  by the tapered surface of the proximal end of the release member  77 . Thereby, the engagement between the rod  100  and the tube part  81  is released, and the rod  100  becomes capable of proceeding to the tip cover  80 . As a result, when the forceps operating portion  13  is advanced, the pair of forceps members  115  and  131  can be opened. As shown in  FIG. 25 , the curved needle  120  is pulled out from the tissue by opening the pair of forceps members  115  and  131 . The suture thread  125  remains like a loop while being passed through the tissue.  
         [0100]     When the suture thread  125  is tightened, the hook sheath  21  is advanced. The hook sheath  21  pushes the distal claw portion  211 , and the distal claw portion  211  pushes the casing  150  from the tip cover  80  toward the tissue. Since the tip cover  80  has returned to the original position, the diameter-increased part  210 A of the guide hole  210  is present around the ball  205 , and the ball  205  is disengaged from the concave portion  202  by the elastic deformation of the leaf spring  206 , so that the engagement between the casing  150  and the casing supporting member  86  is released. When the casing  150  is protruded from the casing supporting member  86 , the hook operating portion  14  is allowed to recede, and the hook  212  is allowed to recede. Since the suture thread  125  engaged with the hook  212  is pulled out, the loop of the suture thread  125  passing through the tissue is narrowed down. Since the handle  16  of the hook operating portion  14  can be pulled beyond the forceps operating portion  13 , the suture thread  125  can be pulled out until the casing  150  is brought into contact with the tissue. As a result, as shown in  FIG. 26 , the incision SO is sutured by the cartridge  153 . In a state in which the incision SO has been sutured, the cartridge  153  is retained in the body by releasing the engagement of the hook  212  or by cutting the suture thread  125  extending from the casing  150  by use of a known thread-cutting treatment device being passed through an operating channel of the endoscope  4 .  
         [0101]     In this embodiment, the structure is formed so that the engagement between the distal-end supporting portion  71  and the tip cover  80  can be released by providing the pin  75  that is a first locking member in the process of allowing the forceps operating wire  15  to recede. Therefore, the detachable needle  121  can be inserted into the casing  150  in accordance with an operation in which the pair of forceps members  115  and  131  is closed while pulling the forceps operating wire  15 . A conventional control portion is complex in structure, and requires much skill in operating. However, in this embodiment, the work including the engagement of the detachable needle  121  can be achieved by a series of operations of the forceps operating portion  13 , and hence the instrument can be easily operated. In other words, for example, in the treatment instrument described by US2003-0181924A1, the hook sheath holding the casing must be moved back and forth to engage the detachable needle with the casing. To do so, the control portion must be shifted from one hand to the other. Additionally, to engage the detachable needle with the casing, the detachable needle and the center axis in the longitudinal direction of the casing must coincide with each other. Therefore, an operator must confirm this coincidence during an operation. In contrast, in this embodiment, since the engagement between the distal-end supporting portion  71  and the tip cover  80  is released when a state in which the tip of the detachable needle  121  can be engaged with the casing  150  is reached, the detachable needle  121  can be inserted into the casing  150  in response to the closing motion of the pair of forceps members  115  and  131 . Therefore, operability is improved. In this embodiment, the suture instrument is disclosed as an example of a treatment instrument. However, without being limited to this, the present invention can be applied to biopsy forceps or grasping forceps that are different in shape from the forceps members  115  and  131 . If the present invention is applied to biopsy forceps, it will become possible to perform the operation of pinching tissues and the operation of removing the tissues, as a series of operations, by an operation performed on the side of the proximal end of the instrument. If the present invention is applied to grasping forceps, it will become possible to perform the operation of pinching tissues and the operation of transferring the tissues, as a series of operations, by an operation performed on the side of the proximal end of the instrument.  
         [0102]     Additionally, the structure is formed so that the link mechanism of the forceps members  115  and  131  and the tip cover  80  can be advanced together by providing the ball  102  that is a second locking member before the pair of forceps members  115  and  131  is opened. Therefore, the pair of forceps members  115  and  131  can be kept closed until the curved needle  120  is completely disengaged from the casing  150 . Since the possibility that interference will occur between the curved needle  120  and the casing  150  is removed, the pair of forceps members  115  and  131  is reliably opened and closed. Additionally, both the disengagement of the detachable needle  121  from the curved needle  120  and the opening motion of the pair of forceps members  115  and  131  are accomplished by a series of operations of the forceps operating portion  13 , and hence the instrument can be easily operated.  
         [0103]     Since the ball  205  by which the casing  150  and the casing supporting member  86  are engaged together is provided as a third locking member, and since the engagement of the ball  205  is controlled by the guide hole  210  of the tip cover  80 , the casing  150  can be reliably fixed, and the detachable needle  121  can be easily engaged with the casing  150 .  
         [0104]     Since the stoppers  151  and  152  that are brought into contact with the tip surface  80 A of the tip cover  80  are provided on the forceps members  115  and  131 , the deviation of the axis of the curved needle  120  can be prevented when the pair of forceps members  115  and  131  is closed. If the deviation of the axis of the curved needle  120  occurs, it will become difficult to insert the detachable needle  121  into the casing  150  or to detach the detachable needle  121  from the curved needle  120 . However, in this embodiment, these problems are solved.  
         [0105]     Since the movement control portion  25  and the scope holder  26  are provided in the path of the insertion portion  3 , and since only the hook sheath  21  or both of the sheaths  21  and  22  are formed to simultaneously move back and forth, the control portion can be more easily operated than a conventional control portion, and the sheath that is moved back and forth by an operator can be easily imagined, thus making it easy to become skillful in operating. Additionally, since the movement control portion  25  is away from the control body  10 , it is easy to share the operations.  
         [0106]     Since the control portion (the forceps operating portion  13 ) that operates the forceps members  115  and  131  and the other control portion (the hook operating portion  14 ) that operates the hook  212  are integrally provided in the control portion  2 , the control portions can be made compact, and can be easily handled. Since the hook operating portion  14  is disposed on the side of the distal end of the instrument, and since the forceps operating portion  13  is formed to enter the space between the handles  16 , the stroke of the hook operating portion  14  can be enlarged, and the suture thread  125  can be easily tightened.  
         [0107]     Various modifications of the suture instrument  1  will be shown hereinafter.  
         [0108]     As shown in  FIG. 27 , a distal claw portion  301  is fixed to the distal end of the hook sheath  21 , and the hook operating wire  18  is drawn therein. Further, the distal claw portion  301  is fixed to the casing holding portion (whose end is slightly opened outwardly in the radial direction so as to receive the casing  150 )  86 . A claw portion  302  is formed integrally with the tip of the distal claw portion  301 , by which the proximal end of the casing  150  can be locked. The distal claw portion  301  is formed by molding the distal claw portion  211  and the step  86 A of the casing supporting member  86  that receives the distal claw portion  211  integrally with each other as shown in  FIG. 9 , and hence both manufacturing costs and the number of assembling steps can be reduced.  
         [0109]     As shown in  FIG. 28 , it is permissible to use a supporting member  310  formed by integrally molding the distal-end supporting portion  71 , the bridge portion  85 , and the casing supporting member  86 . The supporting member  310  is bent like a crank as a whole, and can make component costs and assembly costs lower than a structure in which the distal-end supporting portion  71  and the casing supporting member  86  are formed individually. Metal injection molding, turning center, molding, casting, or forging can be used as the producing method.  
         [0110]     As shown in  FIG. 29 , in a receiving portion  320 , a cut  322  may be formed in a part that is engaged with an outer member  321  to which the tip of the coil sheath  41  is fixed. The receiving portion  320  is used to fix the distal end of the endoscope  4  to a suture instrument  323 . The receiving portion  320  holds the outer member  321  substantially in the cross-sectional shape of the letter C by means of the cut  322 . The position of the cut  322  is a position at which the endoscope  4  and the suture instrument  323  are brought into contact with or close to the inner surface of the overtube  6  when the endoscope  4  and the suture instrument  323  are combined together and are inserted into the overtube  6 . The outer diameter obtained by combining the endoscope  4  and the suture instrument  323  together can be reduced by cutting the receiving portion  320  at this position, and the insertion into the overtube  6  can be easily carried out. The suture instrument  323  has a structure in which the distal claw portion  301  that is engaged with the casing  150  is moved back and forth by a sheath  326 . The distal claw portion  301  is moved back and forth inside the tip cover  80  and a casing holding portion  325  formed integrally with the tip cover  80 .  
         [0111]     As shown in  FIG. 30 , in the receiving portion  320 , a holding portion  330  holding the outer member  321  has the cut  322  so that the cross section thereof has the shape of the letter C, and a tapered surface  331  that is opened toward the distal end is provided. The tapered surface  331  has a curved surface in which the axis line CL of the coil sheath  42  is a center axis. When the tip cover  80  is allowed to recede by operating the hook sheath  21  and the forceps sheath  22 , the proximal end of the casing holding portion  325  is not caught by the receiving portion  320 , and hence the tip cover  80  can be smoothly moved back and forth.  
         [0112]     Although the preferred embodiments have been described as above, the present invention is not limited to these. For example, the present invention can be applied to a rigid endoscope having a rigid insertion portion although a description has been given of a use for the flexible endoscope having the flexible insertion portion in the above embodiments. Various structural additions, exclusions, replacements, and other exchange forms can be executed within the scope not departing from the spirit of the present invention. The present invention is not limited by the above description, and is limited only by the appended claims.