PURPOSE:To restrain higher harmonics on the input side by providing a higher harmonic restrainer. CONSTITUTION:A variable-frequency power supply device is composed of an input power supply 1, a converter device 2, a higher harmonic restraining device 11 connected in parallel with the converter device 2, a smoothing circuit 3 mounted on a DC circuit, an inverter device 4 and load 5 being connected on the output side of the inverter device and receiving the supply of the power supply. The power-supply voltage of the input power supply I is converted into DCs by the converter device 2. A higher harmonic generated on the input side at the time of the conversion is restrained by the higher harmonic restraining device 11, and power-supply waveform distortion is inhibited. When the power-supply voltage of the input power supply 1 is converted into DCs, a ripple is generated, but the ripple is absorbed by the smoothing device 3. DC voltage, from which the ripple is removed, is converted into an AC power supply having arbitrary frequency by the inverter device, and fed to the load 5. Accordingly, the effect of the restraint of the higher harmonic generated on the input side is displayed.