Abstract: The present invention relates to a power factor corrector and a driving method thereof. The present invention includes a transformer including a first coil of a primary side transmitted with an input voltage and a second coil of a secondary side generating an output voltage. A power switch is connected to the first coil, and a capacitor removes a ripple of the output voltage. A diode is connected between the capacitor and the second coil. A resonance is generated between the capacitor and a leakage inductance of the transformer during a turn-on period of the power switch, and a resonance is generated between the capacitor and the magnetizing inductance of the transformer during the turn-off period of the power switch.