PURPOSE: To separate the first winding and second winding from each other by means of inner partitions and to prevent the tilting of the first winding in the axial direction of a stator core by means of the inner partitions by integrally forming the circular-arcuate inner partitions on the upper and lower surfaces of the base sections of three poles together with premolds in such a state that the partitions are protruded inward.

CONSTITUTION: The stator core 10 of this motor is formed by piling up a required number of stator core pieces punched from a hoop. A ring-like yoke section 1 is formed on the outer peripheral side and six pieces of the first winding sections 2 constituting a main pole protruding toward the axis 14 of a rotor 12 are equally arranged on the inner peripheral side. On the outer peripheral section of the yoke section 1, six grooves 8 are arranged at regular intervals in the axial direction. The grooves 8 are provided for guiding the core pieces constituting the stator core 10 when the pieces are fitted to a coil winding machine after premolding. In addition, in order to form in advance an insulating layer at part of the core 10 which comes into contact with the winding and improve the mechanical strength of the core 10, a resin which is called 'premold' is injected.