A heat radiation electrode (15) is exposed from the back surface of an insulating resin (13), and a metal plate (23) is affixed to this heat radiation electrode (15). The back surface of this metal plate (23) and the back surface of a first supporting member (11) are substantially within a same plane, so that it is readily affixed to a second supporting member (24). Accordingly, the heat generated by the semiconductor chip can be efficiently dissipated via the heat radiation electrode (15), the metal plate (23) and the second supporting member (24).