A DC-DC converter reduces a surge voltage developed across a switching element (30) in making the voltage conversion with the use of a transformer (20) inherently having considerable leakage. A snubber circuit is included to absorb the surge energy and transferring it to a load, or output end of the converter, reducing the surge voltage across the switching element (30). A snubber capacitor (51) is provided to absorb the surge energy developed by the transformer (20) when the switching element (30) is off. Thus absorbed energy is collected in a storage capacitor (53) through a reactor (54) while the switching element (30) is on and off, and is then transferred from the storage capacitor (53) to the load, i.e., the output side of the converter, leaving only a minimum voltage being applied across the switching element (30).