A breakdown-voltage control circuit includes a high voltage monitor circuit and a first voltage switching circuit 1112 connected to the high voltage monitor circuit, the high voltage monitor circuit generating a first reference signal based on an input signal inputted to the high voltage monitor circuit, the first voltage switching circuit comparing a first application voltage applied to the first voltage switching circuit with the first reference signal, outputting the first reference signal as a first control signal when the first application voltage is exceeded, and outputting the first application voltage as the first control signal when the voltage of the first reference signal is less than the first application voltage.