Abstract: To accurately regulate output of a high-frequency power with a simple configuration. A high-frequency power supply circuit includes: a basic drive square wave generation circuit unit (5) for generating a basic drive square wave having an output frequency; a differential signal generation circuit unit (9) for generating a front edge differential signal of the basic drive square wave; a vibrator circuit unit (15) having a square wave signal generator (10) for outputting a square wave signal having a signal width within a period corresponding to a half cycle of the output frequency upon input of a trigger signal from outside and signal width control circuits (11, 12) varying/controlling the signal width of the square wave signal according to the control signal; and a switching amplification circuit unit (6) for amplifying the amplification source signal based on the output signal from the vibrator circuit unit (15).