A power conversion device including: an energy storage unit which receives and stores voltage of a self-power-feeding device; and a bypass unit drive device which, when voltage of the self-power-feeding device becomes smaller than a predetermined lower limit value, causes a bypass unit to perform short-circuiting operation by power stored in the energy storage unit. Thus, by appropriately setting the above voltage lower limit value as a threshold value for the short-circuiting operation, it becomes possible to swiftly and reliably perform short-circuiting protection operation even if a cell converter has failed, thus it is possible to always safely continue the operation of the power conversion device.