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 (D11, D12, D13, D14); a transformer (T) magnetically coupling a first winding (W1) and a second winding (W2), 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 in a case where the AC power is transferred in the forward direction and turning off the pair of switches in a case where the AC power is transferred in the backward direction, wherein, in the case of backward direction, current flowing through body diodes (D11a, D12a, D13a, D14a) of the MOSFETs (Q11, Q12, Q13, Q14) of the DC-AC conversion circuit is blocked. a DC-AC conversion circuit using a plurality of MOSFETs; and an AC-DC conversion circuit using a plurality of power diodes (D11, D12, D13, D14); a transformer (T) magnetically coupling a first winding (W1) and a second winding (W2), 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 in a case where the AC power is transferred in the forward direction and turning off the pair of switches in a case where the AC power is transferred in the backward direction, wherein, in the case of backward direction, current flowing through body diodes (D11a, D12a, D13a, D14a) of the MOSFETs (Q11, Q12, Q13, Q14) of the DC-AC conversion circuit is blocked. <EOS>