A treatment instrument used together with an endoscope includes a distal end grasping portion. The distal end grasping portion includes a distal end movable member capable of moving forward and backward along a longitudinal axis of the distal end grasping portion, and a distal end fixation member including a bending portion provided on a distal end side along the longitudinal axis with respect to a tilt portion of the distal end movable member. The bending portion of the distal end fixation member and the tilt portion of the distal end movable member constitute a grasping portion.