A heat dissipation heat sink having a press-fit hole whose inner peripheral surface is a cast skin surface is included; the heat dissipation heat sink is sandwiched by the press-fit head and the insertion guide by aligning the axis of a rectifying element in an insertion guide with the axis of the press-fit hole and making the press-fit head face the heat dissipation heat sink; a protrusion portion of a load receiving jig is made to face the rectifying element in the insertion guide; and the rectifying element is press-fitted into the press-fit hole of the heat dissipation heat sink by pressing the periphery of the press-fit hole of the heat dissipation heat sink (22,23) by the press-fit head and receiving a load applied to the rectifying element by the protrusion portion of the load receiving jig.