PURPOSE: To uniformly resin-seal cavities without deformation and disconnection of a metal wire.

CONSTITUTION: A slide hole 13 for slidably moving a flange 7 and a spring 1 for applying a rebound strength to the flange 7 are so provided at a pedestal 11 that a pot 5a to be introduced with solid resin 12 is vertically vibrated in a mold for sealing a semiconductor device. Further, a tapered surface inclined along inside is formed at an end of the pot 5a. At the time of introducing the solid resin, the pot 5a is closed at an inlet to a runner 6 by an end by means of a recoil strength of the spring 1. After the resin 12 is melted by heat of the mold to become gelled resin 12a, a plunger 9 is lifted, the pot 5a is moved down by pouring pressure at that time, the inlet to the runner 6 is opened, and the resin 12a is poured in cavities 8 at a predetermined pouring speed.