PURPOSE: To facilitate and make sure of voltage regulation by controlling the first and the second timer circuit in CPU and regulating the cycle of a pulse signal and the duty of a chopper circuit.

CONSTITUTION: A voltage to be supplied to a X-ray lamp 15 is regulated by a chopper circuit 11 by making the voltage from an AC power 9 to DC in a rectifier circuit 10. Output voltage of the circuit 11 is converted into high frequency voltage in an inverter circuit 13 and boosted by a heating transformer 14 and applied to the X-ray lamp 15. At this time, a signal from a control unit 16 is inputted to the circuit 11 and the output voltage from the circuit 11, that is, a voltage imposed to the X-ray lamp 15 and filament heating voltage are controlled by the signal. Programmable timers 6 and 7 are controlled by a signal from a CPU 1 in the control unit 16 and the circuit 11 is operated by the output of the timer 7. Thereby, analog regulation by a variable resistor is not necessary and the output voltage becomes stable.