A bearing includes an inner ring and an outer ring arranged to face each other with a rolling element interposed therebetween, and a housing including a housing inner supported by the inner ring and a rotor flange supported by the outer ring. The rotor flange includes a flange portion extending toward one end surface side in an axial direction of the outer ring, and a C-type retaining ring arranged at the other end surface side in the axial direction of the outer ring. A push ring formed of a resin material is provided in a gap between the flange portion and the one end surface in the axial direction.