The invention relates to a bidirectional DC-DC converter with intermediate conversion into AC power, including: a DC-AC conversion circuit using a plurality of MOSFETs; and an AC-DC conversion circuit using a plurality of power diodes; a transformer magnetically coupling a first winding and a second winding, wherein the first winding being electrically connected between the DC-AC conversion circuit AC terminals and being electrically connected between the AC-DC conversion circuit AC terminals in an arrangement such that the AC power generated from the intermediate conversion by an operation of the DC-AC conversion is transferred by the transformer in a forward direction from the first winding to the second winding, and the AC-DC conversion circuit converts the AC power transferred in a backward direction from the second winding to the first winding into DC power; a pair of switches, one of which being inserted in series between respective DC terminals of the DC-AC conversion circuit and the AC-DC conversion circuit and the other of which being inserted in series between another respective DC terminals of the DC-AC conversion circuit and the AC-DC conversion circuit; and a controller being adapted for turning on the pair of switches such that the plurality of power diodes of the AC-DC conversion circuit are reverse-biased where the AC power is transferred in the forward direction and turning off the pair of switches where the AC power is transferred in the backward direction.