The mold device according to the present invention is a mold device to resin-seal the semiconductor device including an insert electrode, and in the semiconductor device, the insert electrode is provided with an insert hole, a nut having a screw hole is disposed in the insert electrode so that the insert hole and the screw hole communicate with each other, the mold device includes a mold body into which resin is injected to resin-seal the semiconductor device, including a side of the insert electrode where the nut is disposed, and a rod-like member that is inserted into the insert hole, and the rod-like member is inserted into the screw hole of the nut through the insert hole of the insert electrode to draw the nut to the side of the insert electrode.