A treatment tool includes an long member； a treatment portion rotatable about a longitudinal axis of the long member； a twisting wire one end of which is connected to the treatment portion, the other end extending toward a proximal end side of the long member； an operating portion, at the proximal end side, that includes a body fixed to the long member, and an operating member configured to rotate around and move along the axis； and a mechanism configured to couple the operating member with the wire and convert a rotation of the operating member into traction of the wire. The body includes a portion configured to come into contact with the operating member to prevent the rotation in a case where the operating member is urged in a direction toward a distal end side of the long member together with the mechanism by a restoring force of the wire.
