To make it possible to further improve the space factor of coil windings 14 in split cores 1.

A part of the coil windings 14 wound around one of a pair of salient poles 13, 13 adjacent in the circumferential direction is formed so as to have a projecting winding shape 14a that extends beyond a boundary line X between both poles. Also, a part of the coil windings 14 wound around the other salient pole 13 is formed so as to have a recessed winding shape 14b that recedes from the boundary line X in order not to interfere with the projecting winding shape 14a formed on the coil windings 14 of the one salient pole 13. This structure makes it possible to wind the coil windings 14, 14 of the salient poles 13, 13 adjacent in the circumferential direction inside a space that appears when wound without extending beyond the boundary X.