A treatment tool includes a transmission member that advances and retracts along a longitudinal axis of an insertion portion to transmit a driving force for rotating the end effector, a first engagement portion provided on a proximal end side of the transmission member, A second locking portion which is provided on the base end side of the sheath and can be engaged with the first locking portion, and a second engaging portion which relatively moves the first locking portion with respect to the second locking portion, A first position in which the transmission member is moved forward along the longitudinal axis of the insertion portion to maintain the end effector in a first state along the longitudinal axis with respect to the distal end portion of the insertion portion, A second position in which the member is moved to the rear side along the longitudinal axis of the insertion portion to maintain the end effector in the second state with respect to the longitudinal axis with respect to the distal end portion of the insertion portion, And a manipulation body capable of switching.処置具は、挿入部の長手軸に沿って進退して前記エンドエフェクタを回動させる駆動力を伝達する伝達部材と、前記伝達部材の基端側に設けられた第1係止部と、前記シースの基端側に設けられ、前記第1係止部に係合可能な第2係止部と、前記第2係止部に対して前記第1係止部を相対的に動作させ、前記伝達部材を前記挿入部の長手軸に沿って前方側に移動させて前記挿入部の先端部に対して前記エンドエフェクタを前記長手軸に沿った第1状態に維持する第1位置と、前記伝達部材を前記挿入部の長手軸に沿って後方側に移動させて前記挿入部の先端部に対して前記エンドエフェクタを前記長手軸に対して回動させた第2状態に維持する第2位置とを切替可能な操作体とを有する。
