(4) In the brush motor 1 of the first example, the coils 7 are connected in an annular shape as illustrated in FIG. 5. Further, with respect to the annular coil circuit, each of the commutator pieces 9 is short-circuit connected every 180 degrees (every 360/p degrees) with respect to the rotation angle of the rotor 6. With such a circuit configuration, the number of brushes can be reduced to 1/p as compared with the existing brush motor, the size of the brush motor 1 can be easily reduced, and the downsizing and the high torque can be achieved with a simple configuration.

(5) The brush motor 1 of the first example includes the two pairs of magnet magnetic poles 5, the three coils 7, and the six commutator pieces 9, and thus, the combination of (p, s, c) is (2, 3, 6). With such a configuration, the brush motor 1 having the high torque can be achieved with a simple configuration in which the number of coils is small, and the downsizing is easy due to an increase in magnetic flux.

FIG. 8 is a cross-sectional view illustrating a structure of a brush motor 41 as a second example. Here, a cross-sectional view of a stator 3 and a rotor 6 is displayed to be superimposed on a cross-sectional view of a commutator piece 9 for the sake of convenience. Elements corresponding to the elements described in the first example are denoted by the identical reference signs, and the description thereof is appropriately omitted. The brush motor 41 includes three pairs of magnet magnetic poles 5, four coils 7, and twelve commutator pieces 9. A combination of (p, s, c) is (3, 4, 12), which is a six-pole/four-slit motor.