A treatment instrument for endoscopes comprising:
- a sheath with flexibility inserted into and removed from an endoscope channel;
- an operation wire disposed within the sheath to be able to advance and retreat;
- an operation unit disposed in a proximal end part of the sheath, having a liquid injection port injecting a treatment liquid into the sheath and operating the operation wire;
- a treatment unit support member having a tube part connected to a distal end part of the sheath and a pair of arm parts extending to a front side from opposite positions to the distal end of the tube part;
- a link mechanism constructed by a pair of opening and closing links which are rotatably connected one ends thereof by a first connection shaft in crossing parts intersecting in an overlapping manner, and a pair of driving links which are rotatably connected one ends thereof to the other ends of the pair of opening and closing links respectively by a second connection shaft and a third connection shaft in an overlapping manner, and are rotatably connected the other ends thereof by a fourth connection shaft in an overlapping manner, in which side surfaces of the driving links and/or the opening and closing links overlapping both side edge parts of the pair of arm parts of the treatment unit support member are in contact while rubbing, a position of the first connection shaft being fixed to the arm part;
- a pair of treatment pieces adapted to extend in a distal end direction from the one ends of the pair of opening and closing links of the link mechanism, and forming a treatment unit performing treatment of an affected area in a living body by a change between a closed state and an open state of the distal end side;
- and
- a forward and backward movement transmission rod to move the fourth connection shaft forward and backward by a forward and backward action force of the operation wire,
- wherein in the treatment unit support member, a concave surface part is formed in an inner surface of the pair of arm parts, the concave surface part being formed into a concave shape in a cross section which is vertical to a longitudinal direction,
- wherein an inner concave wall having a through hole inserting and guiding the forward and backward movement transmission rod is formed in the tube part, and the through hole has a liquid supply part allowing the treatment liquid supplied through an inner side of the sheath to flow out to the pair of concave surface parts, and
- wherein the arm part has a treatment liquid supply path which jets the treatment liquid flowed out of the pair of concave surface parts, in a gap between the concave surface part formed in the inner surface and a side surface of the link mechanism.