PURPOSE: To form the front ends of the outer leads of a plastic molded type semiconductor device to flatly bent shapes without receiving any influences from the burr of a damper, thickness unevenness of plated films, etc., by bending the outer leads in such a way that the front ends are bent downward while the leads are held in a free state after the leads are bent to have Z-forms of a prescribed dimensions.

CONSTITUTION: A preliminary bending process in which outer leads 14 coming out from a resin-sealed section 12 are bent outward after they are bent downward and an adjustment bending process in which the bent front ends of the leads 14 are trued up with an adjustment bending punch while the bent leads 14 are supported by their base sections and the front ends are held in free states are provided. Therefore, the front ends of the outer leads 14 can be trued up when the bending force of the adjustment bending punch is relieved and the external leads can be formed with truedup front ends even when the resin-sealed section 12 of a semiconductor device is bent.