A power conversion device which reduces switching losses and stabilizes the output power. A switching-mode changer generates a reference signal for switching a mode of operation of the full-bridge circuit to a first switching mode or a second switching mode. In the first switching mode, an upper arm and a lower arm are switched synchronously, and a lower arm and an upper arm are non-conducting. In the second switching mode, the lower arm and the upper arm are switched synchronously, and the upper arm and the lower arm are non-conducting. The switching-mode changer adjusts the phase of the reference signal so that the reactive power is reduced.