A semiconductor device according to an aspect of the present invention includes a semiconductor layer, an insulating film formed on the surface of the semiconductor layer, a first insulator embedded in the semiconductor layer with a thickness larger than the thickness of the insulating film, and a resistive element formed on the first insulator. A semiconductor device according to another aspect of the present invention includes a semiconductor layer, an insulating film formed on the surface of the semiconductor layer, a resistive element formed on the insulating film, and a floating region formed on a portion of the semiconductor layer opposed to the resistive element through the insulating film and electrically floating from a periphery thereof.