As illustrated in FIG. 6, the outer circumferential surface 43a of the stator support tube portion 43 in the base portion 40 arranged on the inner side in the radial direction of the stator core 31 has a recess 81. The recess 81 is larger than the protrusion 153 of the caulking dowel portion 150 protruding to the inner side in the radial direction from the inner circumferential surface 31d of the core back 31a when viewed in the axial direction. The six recesses 81 are arranged at intervals of 60° in the circumferential direction. Therefore, the six recesses 81 and the six protrusions 153 protruding from the inner circumferential surface 31d can oppose each other in the radial direction. Each of the recesses 81 has an opposing portion 82 that opposes the protrusion 153 of the caulking dowel portion 150 protruding from the inner circumferential surface 31d in the circumferential direction. Each of the opposing portions 82 overlaps the protrusion 153 of the caulking dowel portion 150 protruding from the inner circumferential surface 31d in the circumferential direction.

The six recesses 81 and the protrusions 153 of the six caulking dowel portions 150 protruding from the inner circumferential surface 31d can oppose each other in the radial direction, and each of the opposing portions 82 overlaps the protrusion 153 protruding from the inner circumferential surface 31d in the circumferential direction, and thus, the stator core 31 and the stator support tube portion 43 in the base portion 40 are positioned relative to each other in the circumferential direction.