A motor having an iron stator, an iron rotor, and an aluminum rear frame serving as a heat sink The stator is fixed onto an inner wall of a housing by an interference fit, and two sets of three-phase windings are wound thereon so that a phase difference between the two sets of windings is (30±60×n)° (i.e., n is an integer), the rotor is provided inside the stator and rotates about a shaft by a rotating magnetic field generated by the stator due to energization of the three-phase windings, and the rear frame is fixed onto the inner wall of the housing by an interference fit, and holds a rear bearing that rotatably supports the shaft on one side of the rear frame in an axial direction.