A power conversion device includes transformers provided with primary windings connected to input terminals and secondary windings including pluralities of single-phase open windings that are insulated to each other; a plurality of converter cells connected to the secondary windings of the transformers; and a control circuit for controlling ON/OFF of switching elements. The converter cells are each include a converter and the inverter that are provided with the switching elements, in which their input ends are connected to the respective single-phase open windings, so that the input ends are connected in mutually parallel fashion, through the transformers, to the input terminal of each phase, and in which their output ends are connected in mutually serial fashion to an output terminal of each phase, to thereby perform three or more-level power conversion.