A treatment tool includes: a support portion which is formed in an axial shape; a treatment portion which is disposed at a distal end portion of the support portion; a treatment assisting portion which is disposed at the distal end portion of the support portion, which has an assisting portion, and in which the assisting portion is capable of being moved between a first position and a second position; a driving portion which moves the assisting portion of the treatment assisting portion; an operation detection portion which determines an amount of movement of the support portion, which is inserted into an introducing tool, with respect to the introducing tool, and an orientation of the support portion; an operating portion which is disposed at a proximal end portion of the support portion; and a control portion which controls the driving portion based on a detection result of the operation detection portion.