To provide a treatment instrument for an endoscope capable of preventing a portion where an operation part is screwed with a connection part from loosening and coming off by a rotational operation during a treatment, and temporarily fixing the orientation of a liquid injection port so that it does not move from a position where liquid injection work can be easily carried out.SOLUTION: A treatment instrument for an endoscope includes: a long cylindrical flexible sheath 2； an operation wire 3 inserted into the cylinder of the flexible sheath 2, which can advance and retreat in an axial direction in the cylinder by being pushed and pulled； a treatment unit provided at the tip of the operation wire 3 for executing a treatment to an affected part； an operation unit 10 for causing the operation wire 3 to advance and retreat； and a liquid injection unit 11 arranged between the flexible sheath 2 and the operation unit 10, which is provided with a liquid injection port 11a for injecting liquid to the treatment unit. The liquid injection unit 11 is screwed with the operation unit 10, and an engagement mechanism 17 is provided for temporarily fixing the screwed state.SELECTED DRAWING: Figure 2【課題】操作部と接続部との螺合した部分が処置中の回転操作より緩んで外れることを防止するとともに、注液口の向きを注液作業がし易い位置から移動しないように仮固定することが可能な内視鏡用処置具を提供すること。【解決手段】長尺円筒状の可撓性シース２と、可撓性シース２の円筒内に挿通され、押し引き操作されることにより該円筒内を軸方向に進退自在な操作ワイヤ３と、操作ワイヤ３の先端に設けられ、患部に処置を行うための処置部と、操作ワイヤ３を進退操作するための操作部１０と、可撓性シース２と操作部１０の間に配置され、処置部に対して送液するための注液口１１ａを設けた注液部１１と、を備え、注液部１１と操作部１０とを螺合により連結する内視鏡用処置具であって、前記螺合状態を仮固定するための係止機構１７を設ける。【選択図】図２
