Semiconductor integrated circuit device

The present invention provides a semiconductor integrated circuit device having an SRAM in which leak current is reduced. In an SRAM comprising a plurality of memory cells each constructed by a storage in which input and output terminals of two inverter circuits are cross-connected and a selection MOSFET provided between the storage and complementary bit lines and whose gate is connected to a word line, a substrate bias switching circuit is provided. In normal operation, the substrate bias switching circuit supplies a power source voltage to an N-type well in which a P-channel MOSFET of a memory cell is formed and supplies a ground potential of the circuit to a P-type well in which an N-channel MOSFET is formed. In the standby state, the substrate bias switching circuit supplies a predetermined voltage which is lower than the power source voltage and by which a PN junction between the N-type well and the source of the P-channel MOSFET is not forward biased to the N-type well, and supplies a predetermined voltage which is higher than the ground potential and by which a PN junction between the P-type well and the source of the N-channel MOSFET is not forward biased to the P-type well.