A yoke (10) is formed cylindrically. A stator (30) comprises a magnet affixed to the yoke (10). A rotor (40) is provided so as to be rotatable relative to the stator (30). The rotor (40) has a coil (42) wound thereon. A shaft (50) is affixed to the rotor (40). A commutator (60) is connected electrically to the coil (42) and rotates with the shaft (50). A brush (70) is in sliding contact with the commutator (60) and supplies an electric current to the coil (42) through the commutator (60). A cooling air flow guide (80) has: a funnel section (81) which is formed in a tapered shape such that theinner diameter thereof decreases gradually from the rotor (40) side toward the commutator (60) side, and which is in contact with or adjacent to the yoke (10) at the radially outer, outer edge of thefunnel section; and a discharge opening (82) through which an air flow is discharged toward the brush (70) from the inside of the funnel section (81).