Provided is a treatment tool including an elongated inserting section that is curveable or bendable, a wire that is disposed from an end effector to a proximal end side of the inserting section through the inserting section, the end effector being connected to a tip of the inserting section, and a power input section that is disposed on the proximal end side of the inserting section and configured to input power to a proximal end portion of the wire, and the wire transmits, to the end effector, power to drive the end effector, and the power input section is configured to increase the power to be input into the proximal end portion of the wire in response to displacement of the proximal end portion of the wire in a longitudinal direction, the displacement accompanying a curve or bend of the inserting section.