A semiconductor integrated circuit that operates on multiple supply potentials including a first potential and a second potential that is higher than the first potential. The semiconductor integrated circuit includes a potential-lowering circuit operating on the second supply potential and including an N-channel MOS transistor that lowers the second supply potential applied to a gate thereof to output a lowered potential from a source thereof, a judging circuit operating on the potential outputted from the potential-lowering circuit and judging whether the first supply potential is high-level or low-level, and a buffer circuit outputting a control signal showing whether the first supply potential is fed based on judgment outputted from the judging circuit.