The present invention relates to an apparatus for setting a communication ID of an energy storage system, the apparatus comprising: a power converter for selecting one power line from among a plurality of power lines to supply power through the selected power line; and battery managers which are sequentially connected to the power converter and are operated by the power selectively supplied through the one power line selected from among the plurality of power lines, wherein the power converter may communicate with one battery manager which is operated by the supplied power from among the battery managers.