To provide a semiconductor device capable of suppressing rise in its temperature and keep the temperature within a predetermined temperature range, to improve the operating speed of the device, and to enable making large chip realization thereof.

In a semiconductor device 1, including a semiconductor chip 11 having a semiconductor substrate (not shown) and an element (not shown) mounted on a surface of a substrate, a Seebeck effect element 21 is provided making contact with at least one of a front face, rear side or side of the chip 11 or in the vicinity thereof, the Seeback element is connected at its positive electrode to a power line 12 of the semiconductor device 1 and at its negative electrode to a grounding power lien 13 of the device 1.