A surgical treatment instrument includes an elongated member an end effector that is bendable with respect to the elongated member, a bending operator operable to bend the end effector, a rotor rotatable about a rotation axis in response to operation of the bending operator, and a transmitter that transmits a driving force to bend the end effector. The bending operator, the rotor, and the transmitter are rotatable about the longitudinal axis together with the elongated member and the end effector.
