An energy management device comprises a first supply/demand information acquisition unit, a second supply/demand information acquisition unit, and a supply/demand management unit configured to determine, based on the first supply/demand information and the second supply/demand information, at least one of (i) an upper limit value of a power amount that the hydrogen generation system can receive from a power grid during a certain period, (ii) a target value of an amount of hydrogen that the hydrogen generation system generates during the certain period, (iii) an upper limit value of a power amount that each of the one or plurality of tri-generation systems can transmit to the power grid during the certain period, and (iv) a target value of a power amount that each of the one or plurality of tri-generation systems generates during the certain period.