The efficiency of inserting a coil conductor into a slot of a stator core is improved in the present invention. Included are a rotor and a stator. The stator includes a stator core formed with a plurality of slots formed at a predetermined depth in a radial direction and arranged while spaced apart from each other in a circumferential direction and stator winding having a coil conductor inserted in each of the slots. A plurality of protrusions are formed in each of the slots of the stator core toward a space into which the coil conductor is inserted.