To supply powers to a plurality of loads by one regulator and reduce the size and cost of the regulator.

A series circuit consisting of a diode D1 and a diode D2 and a series circuit consisting of a diode D3 to which a switching device S3 is connected in reverse-parallel and a diode D4 to which a switching device S4 is connected in reverse-parallel are used as common basic series circuits and series circuits of diodes D(2n+3) to which switching devices S(2n+3) are connected respectively in reverse-parallel and diodes D(2n+4) to which switching devices S(2n+4) are connected respectively in reverse-parallel are provided in accordance with the number (n: positive integer) of loads. With this constitution, powers can be supplied to a plurality of loads by one regulator while special modules such as bidirectional switches, etc., which are required in the conventional constitution are not used.