This treatment instrument, and the major axis member having a longitudinal axis, the long axis member provided at the distal end, and a collection member having a housing portion which is communicated with the opening and the opening is provided at the edge of the opening, the frame portion defining the shape of the opening, said collecting member is connected to at least one of said frame portion, and the volume adjusting member for adjusting the volume of the housing part is connected to the volume adjusting member is disposed along said longitudinal axis and the longitudinal relative to the long shaft member the volume operation member provided to freely advance and retreat in the axial direction, it is connected to the frame part, wherein it is disposed along the longitudinal axis, the long axis member independently of advancing and retracting of the volume control member relative to the long shaft member and comprising an opening operation member which is movably arranged forward and backward to said longitudinal axis, and said opening operation member and the operation means for retracting operate the volume control member and from each other independently of the said longitudinal axis with respect.この処置具は、長手軸を有する長軸部材と、前記長軸部材の先端に設けられ、開口部と前記開口部に連通された収容部とを有する回収部材と、前記開口部の縁に設けられ、前記開口部の形状を規定するフレーム部と、前記回収部材と前記フレーム部との少なくとも一方に接続され、前記収容部の容積を調整する容積調整部材と、前記容積調整部材に接続され、前記長手軸に沿って配置され、前記長軸部材に対して前記長手軸方向へ進退自在に設けられた容積操作部材と、前記フレーム部に接続され、前記長手軸に沿って配置され、前記長軸部材に対する前記容積操作部材の進退とは独立して前記長軸部材に対して前記長手軸方向へ進退自在に設けられた開口操作部材と、前記開口操作部材と前記容積操作部材とを互いに独立して前記長手軸方向へ進退動作させる操作手段とを備える。
