PURPOSE: To make it possible to provide a stable X-ray output without the influence of the ripple of a high voltage power supply on the irradiation X-rays by applying pulse voltage to a grid, while being synchronized with the peak of a rectified voltage applied between the positive and negative electrodes of a triode X-ray tube.

CONSTITUTION: When AC voltage is applied between the primary side terminals (a), (b) of a single-phase transformer T3, a prescribed high voltage is induced on the secondary side, which is rectified through a rectifying circuit 21 to be converted in a pulsating DC voltage. On the other hand, from a PLL circuit 25, a signal having a frequency corresponding to the frequency of the AC power supply described above is outputted, and by ajdusting a phase shifter 27, it is possible to synchronize a pulse signal outputted from a grid control circuit 29 with the peak of a rectified voltage applied between the positive and negative electrodes of the triode-X-ray tube 23. Accordingly, pulse-shaped X-rays having a sharp waveform are radiated from the triode-X-ray tube 23.