<p>A DC-DC converter (1) converts DC power input from one of first and second terminal pairs and outputs the converted DC power to the other one of the first and second terminal pairs. The DC-DC converter (1) comprises: a switching transistor (11S) having a collector connected to the high-voltage side terminal of the first terminal pair and switching the conduction of collector-emitter current; an inductor (121) connected to the switching transistor (11S) in series; another inductor (122) connected in series to a terminal of the inductor (121), to which the switching transistor (11S) is not connected, so as to magnetically couple with the inductor (121); a capacitor (124) connected between the connection point between the inductor (121) and the inductor (122) and the low-voltage side terminal; still another inductor (123) connected between the high-voltage side terminal of the second terminal pair and the inductor (122); and a diode (13D) connected between the connection point between the inductors (122, 123) and the low-voltage side terminal.</p>
