As illustrated in FIGS. 2 and 3, the inner circumferential surface of the magnet 23 opposes outer end surfaces in the radial direction of a plurality of teeth 31b, which will be described later, with a slight gap in the radial direction. That is, the magnet 23 has a magnetic pole surface that opposes the stator 30 in the radial direction. Note that the magnet may have a substantially cylindrical shape surrounding the entire outer circumferential surface of the stator 30. In this case, N and S poles are arranged alternately in the circumferential direction on the inner circumferential surface of the magnet.

The stationary portion 14 includes the base portion 40, the stator 30, a sensor S, and a wiring portion 140 (see FIGS. 8 and 11). As illustrated in FIGS. 2 and 3, the base portion 40 includes: a base cylindrical portion 41 that extends in the axial direction centered on the rotation axis J; a base bottom 42 that spreads to the outer side in the radial direction from a lower end of the base cylindrical portion 41; and a cylindrical stator support tube portion 43 that extends from an outer end in the radial direction of the base bottom 42 to the upper side in the axial direction. The stator core 31, which will be described later, of the stator 30 is fixed to an outer circumferential surface 43a of the stator support tube portion 43.