A three-level power conversion circuit includes a plurality of one-phase switch circuits which receive power from direct current power supplies that are connected in series. Each of the one-phase switch circuits includes a semiconductor switch series circuit that is connected in parallel to the direct current power supplies, and also a bidirectional switch and a circuit-opening device that are connected in series between a series connection point of the semiconductor switch series circuit and a series connection point of the direct current power supplies. If a semiconductor element in a bidirectional switch fails, the circuit opening device opens a path along which the main current of the semiconductor element flows, and operation of the inverter is continued as a two-level inverter with the remaining bidirectional switches in a constant off-state.