Abstract: A bar-like workpiece is axially compressed to form a flange at the intermediate portion thereof. Then, the workpiece with the flange is held by dies and its one axial end surface is received by a receiver die. The receiver die has a recess formed at the central portion of its end surface for accommodating a slug flowing from the workpiece. The end surface of the receiver die around the recess forms a surface to receive the workpiece. From the side opposite to the receiver die a punch is continuously pressed into the workpiece beyond the flange position to form a sleeve insertion hole. Next, a residual material left at the bottom of the sleeve insertion hole is punched out by another punch, completing the fuel injector core.