The commutator 8 is a member for energizing the coil 7 at an appropriate position according to a rotation angle of the rotor 6 in an appropriate orientation. The commutator 8 is provided with c commutator pieces 9 formed in a curved surface shape. A shape of the commutator piece 9 is formed in, for example, an arc surface shape or a shape similar thereto. These commutator pieces 9 are adjacently arranged in the circumferential direction along an outer peripheral surface of the shaft 20. Each of the commutator pieces 9 and each of the coils 7 are connected by a power supply circuit 23. A circuit structure of the power supply circuit 23 will be described later.

A brush 21 (brush) is provided in the periphery of the commutator 8 so as to be in contact with the surface of the commutator piece 9. The brush 21 is attached to one end of a brush arm 22 and is supported in a state of being elastically pressed against the commutator piece 9. In addition, a pair of the brushes 21 and a pair of the brush arms 22 are provided. The other ends of the brush arms 22 pass through, for example, the lid member, extend to the outside of the housing 2 and serve as terminals for power supply.

The brushes 21 are provided so as to be in contact with any one of the c commutator pieces 9.