A semiconductor device includes a heat sink, an insulating layer, a lead frame, a power semiconductor element, a sealing resin, and fins. The heat sink has a first main surface and a second main surface opposed to each other. A lead frame including a lead terminal is disposed on the first main surface of the heat sink with the insulating layer interposed. The power semiconductor element is mounted on the lead frame. The sealing resin is formed to cover an inside region located inside of an outer peripheral region located around the entire periphery along the outer periphery of the first main surface of the heat sink. A first depression is formed along the sealing resin in the outer peripheral region of the first main surface.