SEMICONDUCTOR INTEGRATED CIRCUIT DEVICE

PROBLEM TO BE SOLVED: To provide a semiconductor integrated circuit device having a MOS transistor formed on a SOI substrate, capable of stabilizing the circuit operation without thickening a BOX oxide film and a silicon layer on the SOI substrate even when a power source voltage applied to the semiconductor integrated circuit device is high.SOLUTION: MOS transistors M1 to M9 are formed on the SOI substrate having the silicon substrate, the BOX oxide film, and a silicon active layer, and a bottom of source diffusion layer and a bottom of a drain diffusion layer are formed reaching the BOX oxide film. Enhancement type PchMOS transistors M3,M4,M5,M7 are connected to a power source terminal VDD in which a power source voltage is input, via a depletion type NchMOS transistor M10. The MOS transistor M10 is wired to a source, a gate, and a body to function as a constant current source, and has electric characteristics that a source potential becomes higher than the silicon substrate potential, so a saturation current decreases.