Abstract: A magnetic field core and armature core are provided on a rotor in spaced-apart relation to each other. Windings for producing rotating magnetic poles are positioned on the magnetic field core, and armature windings are positioned on the armature core. The rotor includes a plurality of magnetic sections which are magnetically coupled with the magnetic field core and armature core, but the magnetic sections are magnetically separated from each other in a direction of rotation of the rotating magnetic poles. Magnetic poles produced on the rotor will be coupled together through a magnetic path formed by the rotor and armature core. Thus, by passing three-phase alternating currents, corresponding to the magnetic poles produced on the rotor, through the armature windings, torque is developed in accordance with the Fleming's rule, so that the rotor is caused to rotate as a motor at a synchronous speed.