Stator claw poles are disposed at a stator core at a position facing opposite a rotor so as to alternately range from the two sides along the axial direction. With a plurality of magnetic poles thus formed, the distance by which the gap between the front end portions of the stator claw poles and the stator outer circumference ranges is increased, which, in turn, reduces the reactance guided to a stator coil. It is ensured that the magnetic reluctance manifesting between the front end portions of the stator claw poles and an enclosing member that holds the stator core, facing opposite the centers of the claw poles along the circumferential direction, is greater than the magnetic reluctance manifesting between the front portions and the stator core enclosing member facing opposite the front end portions.