A power control device, power control method, and power control system capable of appropriate power control so that power consumption does not exceed contract power with an electric power company even in the event of a power failure are provided. A power control device installed in a consumer's facility to manage a power state of a load apparatus or a dispersed power source in the consumer's facility, includes: a communicator configured to acquire sensor data relating to the load apparatus or the dispersed power source; a backup power source that is charged with a commercial power source, and supplies power during a power failure; and a controller configured to issue a control instruction to the dispersed power source, when the backup power source supplies power.