Patent ID: 8282543

Claim:
A surgical instrument comprising: an end effector configured to operate on an operating portion in a body cavity; an accommodation portion configured to accommodate the end effector; and an insulating holding member, configured to hold the end effector, is accommodated in the accommodation portion of the end effector, and is configured to advance and retreat along an axial direction of the accommodation portion; an insertion portion having the end effector, the holding member, and the accommodation portion disposed in a distal end portion; movement manipulation mechanism connected to the end effector for moving the end effector to a position at which the end effector is accommodated in the accommodation portion and to a position at which the end effector is exposed from the accommodation portion along an axial direction of the accommodation portion, and moving the holding member along the axial direction of the accommodation portion through the end effector; and a multijointed bending mechanism which is disposed in the distal end portion side of the insertion portion and moves the distal end portion by being bent, the multijointed bending mechanism having: a first bending piece which is the distal end portion of the insertion portion; a second bending piece connected to the first bending piece so as to be rotatable around a first rotation shaft, and arranged on a proximal end side of the multijointed bending mechanism with respect to the first bending piece; a third bending piece connected to the second bending piece so as to be rotatable around a second rotation shaft, and arranged on a proximal end side of the multijointed bending mechanism with respect to the second bending piece; at least two first wires connected to the first bending piece and configured to rotate the first bending piece; and at least two second wires connected to the second bending piece and configured to rotate the second bending piece; wherein the accommodation portion is formed in the first bending piece, and wherein a length from a proximal end portion of the holding member to a distal end portion of the end effector is L 1 , a length of the accommodation portion is L 2 , and a maximum amount of moving stroke of the holding member is L 3 , with L 1 <L 2 and L 3 >L 1 .