A motor includes an armature core having m×n teeth (m is an odd number ≧3, and n is a natural number ≧2), a plurality of coils, and a commutator. The motor further includes field magnets including 2n magnetic poles and at least a first-potential brush and at least a second-potential brush. The commutator includes a segment group defined by 2m×n segments. Only the coil defined by winding a continuous conducting wire in a predetermined winding direction is disposed in each of k teeth among the m×n teeth, and only the coil defined by winding the continuous conducting wire in a direction reverse to the predetermined winding direction is disposed in each of teeth disposed at a position separated from each of the k teeth at 360×i degrees (i is a natural number ≦(n−1)) of electric angles.