To concurrently mold the head section of a rivet by providing recesses formed to nearly match the head section shape of the rivet at the tips of plate press sections and punch sections inserted with the tips into the through holes of the recesses, butted to the rod-like end sections of a rivet raw material inserted into a fastened member, and advanced to press the rod-like end sections.

The tips of plate press sections 2 pinch a fastened member P on both sides to increase the degree of adhesion of the fastened member P and not to generate a gap. The rod-like end sections on both sides of a rivet raw material R are inserted into through holes 22 to the positions kept in contact with the tips of the upper and lower punch main bodies 31 respectively. When a load is applied in the caulking direction via fitting shafts 33 and the punch main bodies 31 are advanced toward the center, the rod-like end sections of the rivet raw material R are gradually compressed and deformed, and a rivet head section is concurrently molded.