To enhance the space factor of coils, reduce the size and improve heat dissipation performance of a split stator by revising the shape of a wire material in the coil outermost layer wound around a slot of the core of the split stator.

Split stators are annularly disposed to configure a stator. Each split stator includes: a core having a tooth portion 11a extended in the radial direction of the stator and having a rectangular sectional shape, a back yoke portion 11b provided at the outer circumferential end of the tooth portion, and a flange provided at the inner circumferential end; an insulating resin layer that is applied to the core, has the circumferential side of the outer circumferential surface of the tooth portion as the bottom face, and is provided with a slot portion for housing a coil whose side faces are composed of the back yoke and the flange portion facing each other; and the coil formed by regularly winding a wire 13 having a polygonal sectional shape in layers in the slot portion. The winding in the outermost layer of the coil is flat and its vertex angle portion at the outer circumferential surface is crushed.