A semiconductor device includes a semiconductor element having a front surface and a rear surface, a pair of heat sinks disposed facing each other so as to sandwich the semiconductor element, and attached respectively to the front surface and the rear surface, and a fastening screw fastening the pair of the heat sinks in the facing direction, the fastening screw having insulation property. Threads are arranged on at least a part of the fastening screw in an axis direction of the fastening screw between the pair of the heat sinks.