A high-frequency power supply device, which outputs high-frequency pulses to a target device on the basis of a synchronous pulse and a clock pulse, and the output control method therefor are such that a period reference signal is generated from output timing information pertaining to the synchronous pulse, an output level signal is generated from output level information, an output stop time is timed on the basis of the period reference signal and an output stop signal is generated, and, when the period reference signal, the output level signal, and the clock pulse are received and a high-frequency pulse is formed on the basis of these signals, transmission of the output level signal is stopped while the output stop signal is being received.