The area information management unit of this energy management system manages at least part of information relating to a plurality of small areas (RA to RD), each of which encompasses some of a plurality of power consumers. Each of the plurality of small areas (RA to RD) partially overlaps at least one other small area of the plurality of small areas (RA to RD). The area information management unit manages information relating to at least one small area of the plurality of small areas (RA to RD) to which a selected power consumer belongs, and information identifying, in addition to that power consumer, other power consumers who are selected by selecting at least one power consumer from each of the at least one small area.