A synchronizing circuit includes an internal partial power supply interruption circuit section which can be subjected to a power supply interruption and includes a data transmission register configured to output data for controlling a power supply interruption and a clock enable control register configured to output an enable signal; an internal partial power supply interruption control circuit section configured to control a power supply interruption and includes a gated clock buffer configured to control a clock signal based on the enable signal, and a data reception register configured to take in data based on the controlled clock signal; and an isolation cell configured to output an output from the internal partial power supply interruption circuit section as a fixed value when the internal partial power supply interruption circuit section has been subjected to a power supply interruption.