Abstract: A conventional semiconductor device has a problem that a frame constituting a heat sink is expensive and the heat sink is highly likely to come off a resin package. A semiconductor device of the present invention reduces the frame price because a heat sink is formed by subjecting a frame with a uniform thickness to pressing or something similar. Furthermore, the heat sink is less likely to come off a resin package because step regions of the heat sink are pressed as connection regions to be connected to the other frame in which leads are arranged, and thereby, resin constituting the resin package goes around the step regions and reaches up to back surfaces of the respective step regions. Moreover, a structure which makes the heat sink much less likely to come off is realized because recessed portions are arranged in the step regions of the heat sink.