To reduce the number of part items while enhancing power factor by placing a correcting resistor for reducing phase delays in currents which occurs in an inductor, in parallel with the inductor which increases a period for which the current is passed through a rectifying diode in the unit cycle of a commercial power supply.

Alternating-current input terminals of a diode bridge 2 for half-wave and full-wave rectification are connected to a pair of commercial power lines 5, 6 of a commercial power supply 1, and an inductor L and a correcting resistor R are connected in parallel with the commercial power line 5, respectively. The inductor L functions so that the inductor increases a time period for which a current is passed through the diode bridge 2 in the unit cycle of the commercial power supply 1, thereby improving the power factor. With the correcting resistor R connected, the maximum value for voltage produced across the terminals of the inductor becomes almost equal to the maximum voltage across terminals when the correcting resistor R is not connected, in spite of the current passing through the inductor L being reduced. As a result, the power factor is enhanced by increasing the period, during which a current is passed through the diodes and reducing the phase delay.