To provide a power conversion device that allows achieving reduction in loss, size, and cost and allows suppressing the probability of breaking of a semiconductor element and deterioration of the power factor, and to provide a method of driving the same.

A power conversion device 1 includes: a primary circuit 1a having a resonant inductor Lr, a switch unit SU, and a primary winding Tra of a transformer Tr; and a secondary circuit 1b supplying energy occurring at secondary windings Trb and Trc side to a load by energization to the primary winding Tra of the transformer Tr. The switch unit SU has first and second diodes D1 and D2 connected in parallel to each other, first and second switch elements S1 and S2, and a resonant capacitor Cr. The secondary circuit 1b further has an output inductor Lo between the secondary winding Trc and the load Vo.