Abstract: A semiconductor device has a MOSFET formed on a single crystalline silicon layer in an SOI structure in which the silicon layer is laminated along with an insulator on a handle wafer. To prevent the body floating effect, a recombination center region is formed connecting to the lower surfaces of source and drain regions of the MOSFET. Consequently, the holes generated within the single crystalline silicon layer just beneath a channel of the MOSFET are injected into the recombination center region by way of the single crystalline silicon layer beneath the source diffusion region and eliminated so that the body floating effect is prevented.