A semiconductor device has a semiconductor support substrate, a buried insulation film disposed on the semiconductor support substrate, and a single-crystal silicon active layer disposed on the buried insulation film. The buried insulation film has portions which have been removed so that remaining portions of the buried insulating film form buried insulating film island regions. The single-crystal silicon active layer has portions which have been removed so that remaining portions of the single-crystal silicon active layer form single-crystal silicon active layer island regions defining single-crystal silicon resistors of a resistance circuit.