A power supply apparatus comprising a converter part (2) for converting an AC voltage to a DC voltage; an inverter part (3) for converting the DC voltage outputted from the converter part (2) to an AC voltage; and a transformer (4), which has an inductance forming a series resonance circuit with an electrostatic capacitance of a load (20), for boosting the AC voltage outputted from the inverter part (3); wherein an inductance (7) is connected, on the output side of the inverter part (3), in parallel with the transformer (4), whereby no or less recovery current flows through a free wheel diode in the inverter part (3) during discharging and no lighting in a discharging part (6) of the load (20), so that the heating of the free wheel diode can be suppressed without providing additional free wheel diodes. |