A power supply potential detecting circuit detects a power supply potential of a second circuit block when a first circuit block shifts from a power supply shutdown state to a power supply feeding state or shifts from the power supply feeding state to the power supply shutdown state. Then, an operation control circuit temporarily stops a function of the second circuit block when the first circuit block shifts from the power supply shutdown state to the power supply feeding state or shifts from the power supply feeding state to the power supply shutdown state and then recovers the function of the second circuit block based on a detection result outputted from the power supply potential detecting circuit.