To make it possible to achieve the low cost and the compact configuration under the especially heavy load conditions and to improve power conversion efficiency by improving power factor based on the switching output, which is fed back from a series resonance circuit to a rectified current path.

A voltage doubler rectifier circuit is provided in a power-factor improved converter circuit, and the correspondence to heavy-load conditions can be achieved. As the power-factor improved converter, a power-factor improved converter part 11 is provided. In the power-factor improved converter part 11, a filter choke coil LN is inserted in series with a positive-electrode line of a commercial AC power supply AC, and a filter capacitor CN is inserted in parallel with both electrode lines of the commercial AC power supply AC and forms the multi-mode low-pass filter together with the filter choke coil LN. Then, the rectifier circuit system comprising rectifying diodes D1-D4 and smoothing capacitors Ci1-Ci4 is provided for the commercial AC power supply AC, and a quadruple-voltage rectifier circuit is formed.