A movable support at least partially supports a final output shaft and a driving mechanism, and is integrally movable relative to a housing in an axial direction of a driving axis. A biasing member biases the movable support toward a front side in the axial direction. A first guide shaft extends in the axial direction and slidably guides the movement of the movable support in the axial direction. At least one intermediate shaft rotates in response to rotation of a motor shaft and transmit power of the motor to the driving mechanism. At least one bearing supports an end portion of the at least one intermediate shaft is located in the front side in the axial direction. A single metal support is immovable relative to the housing and supports the at least one bearing. The single metal support has a first hole for partially receiving the first guide shaft.