To provide a manufacturing apparatus which has excellent electric characteristics and can improve the core accuracy without complicating the apparatus.

Steel plates 22 each formed with a necessary hole 21 are sequentially laminated in one rotating direction at a predetermined angle, the weldable parts of the holes 21 deviated stepwise by the laminating are sequentially connected by laser spot welding from the oblique direction to the laminating direction of the core. As a result, since the connections of the laminated steel plates are sequentially conducted by laser spot welding, the residual stress and deformation like conventional press injection do not occur. Even if padding occurs by welding, there is a hole space in the protubelance direction and hence the close contact of the plates is not disturbed.