Semiconductor integrated circuit device

A semiconductor integrated circuit device includes a first flip-flop circuit receiving data in synchronization with a first clock signal, a logic circuit performing a predetermined process on data output from the first flip-flop circuit, a hold buffer delaying transmission of an output of the logic circuit, a second flip-flop circuit receiving an output of the hold buffer in synchronization with a second clock signal, and a power supply circuit capable of selecting a supply of a power supply voltage to the first flip-flop circuit, the logic circuit, and the second flip-flop circuit between a first power supply voltage and a second power supply voltage higher than the first power supply voltage. A power supply voltage supplied to the hold buffer remains the same when the power supply voltage supplied to the first flip-flop circuit, the logic circuit, and the second flip-flop circuit changes between first and second power supply voltages.