A stator is press fitted into a recess of a casing. The recess has a chamfered portion. The chamfered portion is arranged between an inlet opening end of the recess and a bottom of the recess in such a manner that a width of the recess is progressively increased along the chamfered portion from a bottom side toward an inlet opening end side of the recess. The chamfered portion has a plurality of slant surfaces, which are arranged one after another in the press fitting direction of the stator. Angles of the plurality of slant surfaces with respect to the press fitting direction of the stator decrease from the inlet opening end side of the recess toward the bottom side of the recess.
