PURPOSE: To obtain the product of high strength which does not produce any cracking by concentrically shifting rupture structures to the central part to be formed with hole and blanking the central part in piercing process in pressure-molding the ring body by using the blank provided with shear-cut rupture structures at the end face of the cutting part.

CONSTITUTION: An iron-made round bar blank 12 having been cut to the specified size is heading-molded by using the punches 7 thru 10 provided with spherical protruding parts and the intermediate dies 2 thru 5 provided with step parts to shift the shear cut rupture structures S, S' appearing in the end face of the cutting part of the blank to the end face S3 of the small cylindrical part 12g and the bottom S3' of the semi-spherical recess 12f. Thence, if the blank 12' is fitted to the piercing die 6 of the final process and the central part is blanked by a punch 11, the small cylindrical part 12g' is borken down at the step part 12h and a through-hole 12i is formed, whereby the ring body 13 free from rupture structures is obtained. By this method, the product of high quality may be volume-produced without requiring excess workings.