a pinion movable body described later a shift lever 7 a pinion pushing solenoid 8 a battery 9 and a motor electrification switch 10 in the present embodiment directions can be defined such that longitudinal directions of the output shaft 6 are axial directions ax radially extending directions from the output shaft 6 along a plane perpendicular to the axial directions are radial directions ra and directions circulating around the axial directions along the plane perpendicular to the axial directions are circumferential directions cr the motor 5 generates torque in response to current supply thereto the output shaft 6 rotates being transmitted with the torque generated by the motor 5 the pinion movable body is provided such that it is axially movable on the outer periphery of the output shaft 6 the pinion pushing solenoid 8 has a function of pushing the pinion movable body in the direction opposite to the motor leftward in fig1 via the shift lever 7 the motor electrification switch 10 opens closes a motor contact which is provided at a motor circuit to pass current from the battery 9 see fig3 to the motor 5 the motor 5 is an electric dc motor with a brush including a field magnet 11 armature 14 and a brush 16 the field magnet 11 is configured by a plurality of permanent magnets the armature 14 includes an armature shaft 12 with its one end being provided with a rectifier 13 the brush 16 is arranged being in contact with an outer peripheral surface of the rectifier 13 hereinafter referred to as a u201c rectifier surface u201d and pressed against the rectifier surface by a brush spring 15 see fig9 the field magnet 11 of the motor 5 which is made up of the permanent.