Fixing a semiconductor element to a substrate, electrically connecting signal and main terminals to the semiconductor element, a terminal aggregate includes a frame portion, the signal terminal, the main terminal, which has a larger width than the signal terminal, and a dummy terminal, and forming a to-be-encapsulated body in which the substrate, the semiconductor element, and the terminal aggregate are integrated, mounting the to-be-encapsulated body on a lower mold half such that a plurality of blocks formed in the lower mold half are meshed with the signal, main, and dummy terminals with no space left therebetween after the mounting, placing a bottom surface of an upper mold half on top surfaces of the plurality of blocks, and top surfaces of the signal, main, and dummy terminals to form a cavity for the substrate and the semiconductor element, and performing molding by injecting mold resin into the cavity are included.