The magnet 4 illustrated in FIG. 1 is formed by combining four magnet pieces in which one magnetic pole pair is magnetized in one piece, but may be formed by combining magnet pieces in which a plurality of magnetic pole pairs is magnetized in one piece. Alternatively, a tubular magnet (ring magnet) that is not divided into a plurality of magnet pieces may be used as the magnet 4. In the ring magnet, the plurality of magnet magnetic poles 5 (magnetized regions) is adjacently arranged in the circumferential direction, but a non-magnetized region may be provided between the magnet magnetic poles 5. The non-magnetized region is a region that does not substantially contribute to formation of the magnetic field with respect to the rotor 6, and is a portion corresponding to a gap between the magnet magnetic poles 5 illustrated in FIG. 1. In this manner, it is unnecessary for a physical division number of the magnet 4 to match a magnetic division number.

The rotor 6 is provided with a core 10 (rotor core) and a commutator 8 (commutator) that are fixed to the shaft 20 in a relatively non-rotatable manner. The core 10 is formed by laminating a plurality of steel plates having the identical shape. A lamination direction of the steel plates is identical to an extending direction of the rotation axis C. The core 10 is provided with s teeth 11 having a shape radially protruding from the rotation axis C in the cross section perpendicular to the rotation axis C. Electric wires are wound respectively around the teeth 11 to form s coils 7 (concentrated-winding coils).