As an object of reducing a noise resulted from the mutual influences between circuit-configuring components, a DC-DC converter includes a high voltage circuit section that is electrically connected to a transformer, a low voltage circuit section that is electrically connected to the transformer, a housing in which the high voltage circuit section and the low voltage circuit section are accommodated, a control circuit board that controls the driving of the low voltage circuit section, and a frame that supports the control circuit board. The frame is arranged on a position facing a bottom surface of the housing while crossing the low voltage circuit section. The housing includes a first wall that separates a first space in which the high voltage circuit section is accommodated and a second space in which circuit components configuring the low voltage circuit section are accommodated. The frame forms a second wall that protrudes toward a direction approaching a leading end of the first wall.