The purpose of the present invention is to suppress noise due to a gap between a rotor and a plate even when there are dimensional variations in members or assembly states. In a configuration providedwith: front-side and end-side stator assemblies (200, 300); a rotor (400) provided with a rotor member (402) and a shaft (403) accommodated in the stator assemblies (200, 300); and a front plate (210) and an end plate (310) which are disposed on both sides in the axial direction of the stator assemblies (200, 300) and which connect the stator assemblies (200, 300), an annular projection (700) protrudes from a surface of the front plate (210) opposing the rotor member (402), a coil spring (800) interposed between the front plate (210) and the rotor member (402) is contained inside the projection (700), and the rotor (400) is urged toward the end plate (310) by the coil spring to elastically press the rotor (400) onto the end plate (310).