PURPOSE: To provide a small-sized high voltage generating circuit which outputs a high voltage with high precision.

CONSTITUTION: The high voltage outputted from a high voltage generating circuit 2 for generating a high voltage is outputted as the output voltage charged in an output circuit 3. The charged voltage is discharged by an electric discharge circuit 4, and the output voltage lowers. A neural net 6 receives the output voltage and the output timing of the output voltage and outputs a control signal S for controlling the high voltage generating circuit 2 or the electric discharge circuit 4. A control part 1 controls the high voltage generating circuit 2 or the electric discharge circuit 4 according to the control signal S, and a prescribed voltage is outputted from the output circuit 3.