To provide a high voltage generator capable of making an output voltage achieve a target voltage in a short time without generating an overshoot or an undershoot.

When the polarity is switched from a state in which the DC voltage of a prescribed polarity is being output to a state in which a DC voltage of a polarity opposite to the prescribed polarity is output, the high-voltage generator is set to raise a DC voltage at a variation ratio according to the DC voltage of the prescribed polarity and a target voltage during a period of a transient state until attainment of the target voltage of the opposite polarity.