A plurality of salient poles projecting toward a stator are arranged on a rotor core along the circumferential direction while being spaced apart from each other, and rotor windings are wound around these salient poles. The rotor windings are short-circuited through diodes, respectively; and when currents rectified by the diodes flow through the rotor windings, the salient poles are magnetized to produce a magnet where the magnetic pole is fixed. The width θ of each salient pole in the circumferential direction is smaller than a width corresponding to an electric angle of 180° of the rotor, and the rotor windings are wound around each salient pole by short-pitch winding.