Disclosed is a multiphase DC-DC converter including a plurality of DC-DC converter circuits connected in parallel to one another; an output section to add up outputs of the plurality of DC-DC converter circuits to obtain one output; a timing generating circuit to generate timing signals for respectively operating the plurality of DC-DC converter circuits; a control circuit to selectively and sequentially operate the plurality of DC-DC converter circuits in synchronization with the timing signals outputted from the timing generating circuit so that output phases of the plurality of DC-DC converter circuits are different from one another; and a current detection circuit to detect an output current of each of the plurality of DC-DC converter circuits, wherein the control circuit selects one of the plurality of DC-DC converter circuit to be operated next based on an output of the current detection circuit.