The treatment instrument includes a major axis member (2) is provided at the leading end of the long axis member (2) (2a), operable treatment portion between the first position and a second position (3) It is connected to the treatment unit and the treatment unit (3) and (3) a longitudinal axis relative to the major axis member (2) the driving force transmitting member (30) which extends movably along (2c), the operation unit (6), and the driving force transmission to the operating amount of the operating unit (6) as well is operated with the operating unit (6) the operation amount a first position and a second position the treatment section (3) depending on the I and a switching means (20) for switching the ratio of the amount of movement of the member (30).この処置具は、長軸部材(2)と、長軸部材(2)の先端部(2a)に設けられ、第1の位置と第2の位置の間で動作可能な処置部(3)と、処置部(3)と接続され処置部(3)を長軸部材(2)に対して長手軸(2c)に沿って移動自在に延設された駆動力伝達部材(30)と、操作部(6)と、操作部(6)の操作量に応じて処置部(3)を第1の位置と第2の位置との間で動作させると共に操作部(6)の操作量に対する駆動力伝達部材(30)の移動量の比を切り替える切替手段(20)とを備える。
