A semiconductor device comprising: at least one semiconductor module having a semiconductor element (51a through 56a) functioning as a heater element, a resin mold having a plate shape and covering the semiconductor element, and a heat radiation plate covered by the resin mold, exposed from one surface of the resin mold, insulated from the semiconductor element, and radiating heat generated in the semiconductor element; and a cooler disposed on a surface of the semiconductor module where the heat radiation plate is exposed, providing a refrigerant passage , and promoting radiation of heat from the heat radiation plate by flowing a refrigerant through the refrigerant passage, wherein: the heat radiation plate includes fins provided by pulling up a surface of the radiation plate along one direction (y) linearly; and the fins have a tapered shape with an elliptical arc shape curved from a base to a tip, characterized in that the surface of the radiation plate includes a protruding surface of fin portions and a recessed surface ; the recessed surface is provided by a skived side of the surface of the radiation plate ; and the protruding surface is provided by an inner portion opposite to the skived side; and a skiving direction (B1) of the multiple fin portions has an acute angle (α) with respect to the refrigerant flow direction (A1), the angle being greater than 0° and not greater than 45°. at least one semiconductor module having a semiconductor element (51a through 56a) functioning as a heater element, a resin mold having a plate shape and covering the semiconductor element, and a heat radiation plate covered by the resin mold, exposed from one surface of the resin mold, insulated from the semiconductor element, and radiating heat generated in the semiconductor element; and a cooler disposed on a surface of the semiconductor module where the heat radiation plate is exposed, providing a refrigerant passage , and promoting radiation of heat from the heat radiation plate by flowing a refrigerant through the refrigerant passage, wherein: the heat radiation plate includes fins provided by pulling up a surface of the radiation plate along one direction (y) linearly; and the fins have a tapered shape with an elliptical arc shape curved from a base to a tip, characterized in that the surface of the radiation plate includes a protruding surface of fin portions and a recessed surface ; the recessed surface is provided by a skived side of the surface of the radiation plate ; and the protruding surface is provided by an inner portion opposite to the skived side; and a skiving direction (B1) of the multiple fin portions has an acute angle (α) with respect to the refrigerant flow direction (A1), the angle being greater than 0° and not greater than 45°. the heat radiation plate includes fins provided by pulling up a surface of the radiation plate along one direction (y) linearly; and the fins have a tapered shape with an elliptical arc shape curved from a base to a tip, characterized in that the surface of the radiation plate includes a protruding surface of fin portions and a recessed surface ; the recessed surface is provided by a skived side of the surface of the radiation plate ; and the protruding surface is provided by an inner portion opposite to the skived side; and a skiving direction (B1) of the multiple fin portions has an acute angle (α) with respect to the refrigerant flow direction (A1), the angle being greater than 0° and not greater than 45°. <EOS>