To facilitate the assembly of a motor and a rotation sensor by reducing man-hour for assembling the motor and the rotating sensor, and facilitating positioning the rotation sensor in a motor supporting structure for supporting an electric motor.

This structure involves a housing 4 having a peripheral wall 4b extending in the axial direction of a rotating shaft and a partition wall 4a expanding in the radial direction of a rotating shaft, a stator 2 fixed to the housing 4, a motor 1 which has a rotor 3 facing a stator 2 and is rotatably supported by a housing 4, and a motor support 10 on which a rotating sensor 6 detecting the rotational speed of the rotor 3 is fixed. The stator 2 is fitted into the inner peripheral wall of the housing 4, the motor support 10 is fitted between the rotating shaft and the inner peripheral wall of the housing 4, and the motor 1 is clamped between the motor support 10 and the partition 4a.