Heat radiation surfaces 7b and 8b of electrode lead frames 7 and 8 make thermal contact with heat radiation members 301 via insulation sheets 10 to dissipate heat from a power semiconductor element 5 to the heat radiation members (thick portions 301). Each of exposed areas of the heat radiation surfaces 7b and 8b and a surface 13b of a mold material (sealing material 13) adjacent to the exposed area produce an uneven step from which either one of the exposed area and the surface 13b adjacent to the exposed area projects. The step side surface formed between the convex surface and the concave surface of the uneven step has an inclined surface 7a or 13a so configured that an obtuse angle can be formed by the inclined surface and the convex surface and by the inclined surface and the concave surface for each.