A semiconductor module includes a case including a receiving space that is formed by a frame portion and a pair of wall portions disposed to face each other with the frame portion therebetween. The wall portion includes a heat-dissipation portions and a support wall that supports the heat-dissipation portions at the frame portion, and the wall portion includes a heat-dissipation portion and a support wall that supports the heat-dissipation portion at the frame portion. The heat-dissipation portions provided at the wall portion are separately provided by being disposed to face a plurality of semiconductor device blocks respectively. A plurality of separate heat-dissipation portions is surrounded by the support wall, the support wall is deformed to recessed from the frame portion through the separate heat-dissipation portions inside the case such that a plurality of insulating sheets is closely joined to a plurality of lead frames and the plurality of heat-dissipation portions.