A brush holder extends substantially in a radial direction of a commutator. The brush holder includes a first inner side surface and a second inner side surface, which are separate from each other in the axial direction of the commutator. A torsion spring presses portions-to-be-pressed of a brush-rear end, thereby urging the brush toward the commutator. The portions-to-be-pressed are deviated from a brush-center line in the axial direction of the commutator. The brush is urged by the torsion spring, thereby bringing a brush-tip end into contact with the first inner side surface, and bringing the brush-rear end into contact with the second inner side surface.