It is an object of the present invention to make it possible to easily wind a stator winding, enhance an occupied ratio in a stator core, reduce a winding resistance because there is no coil end, and change a field magnetic flux in accordance with a use.Stator pawl magnetic poles of a stator core extend from both sides in an axial direction alternately at locations opposed to a rotor to form a plurality of magnetic poles. With this stator core, it is only necessary to annularly wind a stator winding. Therefore, it is possible to enhance operability and an occupied ratio, and since there is no coil end, it is possible to reduce winding resistance. Since the rotor is a Randall type rotor having a field winding and a rotor pawl magnetic pole, it is possible to change the field magnetic flux in accordance with a use.