PURPOSE: To integrally form with high efficiency a container in complicated shape, etc., by subjecting the metal plate of super plasticity to deep drawing by a press in a preform and finishing it with a hot bulging method by heating in a super plastic temp. zone.

CONSTITUTION: A regular square cylinder primary formed part 8 is obtd. by deep-drawing a two phase stainless steel plate by the press using an ordinary die. Then, the square cylinder formed part 8 obtd. by the primary forming is fitted to the female die 9 of the bulging die, fastened by bolt by keeping the whole periphery of the flange airtightly by beads and fitted to a bulging machine. In succession, it is heated to a superplastic temp. with ventilating an Ar gas in this state and the gas pressure is increased after reaching the specified temp. the preform shows a superplastic phenomenon by this heating and the increased gas presssure and the wall of the primary formed part is bulged toward the female die of sharp angle coming into contact with the external face. The square cylinder formed part having an acute angle corner part is thus obtd. in a short time.