In the power supply composed of a driver circuit generating the carrier, a resonance circuit driven by the carrier and a rectification circuit generating the dc voltage by rectifying the amplitude-modulated carrier supplied by the resonance circuit and stabilizing the output voltage by the feeding back the voltage error between the output voltage and a reference voltage externally supplied to set up the output voltage, to the frequency and the amplitude of the carrier, the frequency response of the dc power supply is improved both by providing the pole located at the origin with a transfer function where the dc voltage, generated by rectifying and smoothing the output of the resonance circuit, is fed back to the frequency of the carrier and by not providing the pole at the origin with a transfer function where the dc voltage is fed back to the amplitude of the carrier.