In order to achieve an object to reduce a surge voltage and suppress noise generation, the present invention provides a DC-DC converter with a snubber circuit, which boosts a voltage Vi of a DC power supply. The snubber circuit includes: a series circuit connected to both ends of a smoothing capacitor Co and including a snubber capacitor Cs and a snubber resistor Rs; a snubber diode Ds1 connected to a node at which the snubber capacitor Cs and the snubber resistor Rs are connected, and to a node at which a reactor Lr1 and an additional winding 1b of a transformer T1 are connected; and a snubber diode Ds2 connected to the node at which the snubber capacitor Cs and the snubber resistor Rs are connected, and to a node at which a reactor Lr2 and an additional winding 2b of a transformer T2 are connected.