A phase-synchronized RF power generator includes: an RF power amplifier for amplifying an RF power signal; a first directional coupler; an isolator for adjusting impedance mismatch generated by the first directional coupler, and transferring the RF power signal transferred by the first directional coupler to the output terminal; a second directional coupler for transferring part of the feedback signal transferred by the first directional coupler to be compared with a frequency of a reference signal provided by a crystal oscillator, and transferring rest of the feedback signal to a feedback loop; a digital phase shifter for adjusting a phase of the feedback signal transferred by the second directional coupler at predetermined intervals; an analog phase shifter for continuously adjusting the phase of the feedback signal discretely adjusted by the digital phase shifter; and a frequency comparator.