A semiconductor device comprising: a first substrate on which a semiconductor element is mounted; a positive-side power terminal , a negative-side power terminal , an output-side power terminal , positive-side control terminals and negative-side control terminals connected to the semiconductor element ; a heat-dissipating plate ; an insulating layer disposed between and electrically insulating the first substrate and the heat-dissipating plate ; and molding resin that molds the first substrate , the heat-dissipating plate , the positive-side power terminal , the negative-side power terminal , the output-side power terminal , the positive-side control terminals , and the negative-side control terminals and the insulating layer , the heat-dissipating plate being rectangular and having first and second edges opposed to each other and a first surface opposite to the insulating layer , the first surface being exposed from the molding resin , and the insulating layer having first and second curved portions respectively facing the opposing first and second edges of the heat-dissipating plate , each curved portion being bent towards the first surface along a side of the heat-dissipating plate , wherein end portions of the insulating layer are located in the molding resin , the curved portions have a length shorter than a thickness of the heat-dissipating plate , the positive-side power terminal , the negative-side power terminal , the output-side power terminal , the positive-side control terminals and the negative-side control terminals are exposed from the resin , characterized in that the curved portions of the insulating layer are not in contact with the respective sides of the heat-dissipating plate and are located farther from the respective sides of the heat-dissipating plate as the curved portions approach the first surface. a first substrate on which a semiconductor element is mounted; a positive-side power terminal , a negative-side power terminal , an output-side power terminal , positive-side control terminals and negative-side control terminals connected to the semiconductor element ; a heat-dissipating plate ; an insulating layer disposed between and electrically insulating the first substrate and the heat-dissipating plate ; and molding resin that molds the first substrate , the heat-dissipating plate , the positive-side power terminal , the negative-side power terminal , the output-side power terminal , the positive-side control terminals , and the negative-side control terminals and the insulating layer , the heat-dissipating plate being rectangular and having first and second edges opposed to each other and a first surface opposite to the insulating layer , the first surface being exposed from the molding resin , and the insulating layer having first and second curved portions respectively facing the opposing first and second edges of the heat-dissipating plate , each curved portion being bent towards the first surface along a side of the heat-dissipating plate , wherein end portions of the insulating layer are located in the molding resin , the curved portions have a length shorter than a thickness of the heat-dissipating plate , the positive-side power terminal , the negative-side power terminal , the output-side power terminal , the positive-side control terminals and the negative-side control terminals are exposed from the resin , characterized in that the curved portions of the insulating layer are not in contact with the respective sides of the heat-dissipating plate and are located farther from the respective sides of the heat-dissipating plate as the curved portions approach the first surface. <EOS>