PURPOSE: To reduce a cost for a DC power supply equipment capable of improving an input current waveform and a power factor and also to suppress an increase in higher harmonics component in the input current waveform even though an input AC voltage is high.

CONSTITUTION: A switching element 15 is connected to the output of a rectifying circuit 8 for full-wave rectifying AC voltage through a reactor 13. An error output between an output voltage and a reference voltage is synthesized with chopping wave, further instantaneous values of the AC voltage which are synthesized only when the AC voltage is high is given to one of the input terminals of a comparator 25, and a detected value of a current flowing through the switching element 15 is given to the other input terminal of the comparator. A flip-flop 31 is set by the rising of the triangular wave and reset by an output of the comparator 25 to produce PWM wave, and the switching element 15 is ON-OFF controlled.