To efficiently manufacture thinner core strips by laminating and assembling stator laminated cores and rotor laminated cores for a rotary electric machine, without causing product performance to deteriorate.

A manufacturing method of the core strips includes processes of: uncoiling a coil 20 of a band type magnetic steel plate which is a material of the core strips 5, and feeding out the material steel plate at a predetermined speed; cutting out the core strips; and accumulating the core strips thus cut out in an accumulation box. In the process of cutting out the core strips, a cutter roller 26 and a receiving roller 27 are arranged facing the peripheral surfaces and confronting each other, wherein the cutter roller is a cylindrical type, and a convex-type cutting edge which fits to a shape of the core strips to be manufactured is formed on its outer peripheral surface, while the receiving roller is a cylindrical type and has a smooth outer peripheral surface. The material steel plate fed out between the both rollers is held therebetween, while being made to synchronously rotate in the direction opposite to each other, and the material steel plate is pressed and cut by the convex-type cutting edge between the convex type cutting edge of the cutter roller and the outer peripheral surface of the receiving roller, and then the core strips of the shape corresponding to the shape of the convex-type cutting edge is cut out.