To provide a high voltage AC power supply which can produce an AC voltage having arbitrary output waveform and frequency over a wide range from DC to AC.

An AC voltage control means 5 operates the peak voltage of high voltage DC power supplies 1, 2 depending on the amplitude of an AC voltage outputted from a high voltage AC power supply and sets a negative polarity control means 6 and a positive polarity control means 7. The positive polarity control means 7 performs constant voltage control such that the output voltage from the high voltage DC power supply 2 has a level set by the AC voltage control means 5. Similarly, the negative polarity control means 6 performs constant voltage control of the output from the high voltage DC power supply 1. A polarity selecting means 3 delivers the outputs from the high voltage DC power supplies 1, 2 subjected to constant voltage control selectively to an output terminal 4 thus outputting an AC voltage. According to the arrangement, an AC voltage having an arbitrary frequency from DC to several kHz and an arbitrary amplitude can be outputted.