PURPOSE: To eliminate warp of a heat-dissipating panel and cracking on an element, by providing metallic plates, which are the same as the heat-dissipating panel or whose thermal expansion coefficient is similar to that of the heat-dissipating panel, onto two mutually facing surfaces of a resin section of a resin-sealing device.

CONSTITUTION: Onto a heat-dissipating panel of copper, etc., a semiconductor element 2 is soldered, and it is connected to a wire 6 and sealed by resin 3, and then, a metallic plate 4, which is same as the heat-dissipating panel 1 or whose thermal expansion coefficient is similar to that of the heat-dissipating panel 1, is attached onto the surface. In this mechanism, thermal distortion occurring between the heat-dissipating panel 1 and the resin 3 and also between the resin 3 and the metallic plate 4 are offset, and the heat-dissipating panel can be prevented from warp even when it is in a state of high temperature. And therefore, even at the time when this heat-dissipating panel was attached to an outside heat-dissipating unit, the thermal conductivity is not deteriorated, and the element 2 can be prevented from occurrence of crack.