PURPOSE: To shorten the potential restoring time of a high DC voltage by providing a high-voltage control section incorporating transistors which are connected in series between a low- or high-potential side output terminal and earth potential and selectively turned on in accordance with the voltage outputted from the low- or high-potential side output terminal.

CONSTITUTION: A high-voltage control section HVC is composed basically of transistors Q1-Q5 which are connected in series like a totem pole between the low-potential side output terminal of a high-voltage generating section HVG and an output earth potential GO. The section HVC also has a voltage-dividing circuit incorporating capacitors C2 and C3 connected in parallel with resistors RB and RC and the voltage-dividing circuit forms a prescribed divided-potential VD by dividing a high DC voltage HV outputted from the high-potential side output terminal HV+ of the high voltage generating section HVG in accordance with the resistance ratio between the resistors RB and RC. Therefore, the transistors Q1-Q5 are selectively turned on in accordance with the potential of the a control voltage VC, namely, the high DC voltage HV and control the potential of the high DC voltage VC by changing the reference potential at HV-.