A semiconductor device comprises an Si substrate, an isolation insulating film formed on the Si substrate, an Si layer formed on the Si substrate, a gate oxide film formed on the Si layer, a gate electrode formed on the gate oxide film, a sidewall formed on the side face of the gate electrode, a gate silicide film formed on the gate electrode, source and drain regions formed at both the sides of the gate electrode and including a part of the Si layer, and a silicide film formed on the source and drain regions. Because the source and drain regions are formed on a layer-insulating film so as to be overlayed, it is possible to decrease the active region and cell area of a device. Thereby, a high-speed operation and high integration can be realized.