Abstract: To integrally manage energy for a plurality of districts and optimize energy supply and demand of the plurality of districts. In order to manage energy for a plurality of districts including a plurality of facilities, an energy management system includes a management computer connected to the plurality of districts via a communication network. The management computer stores, for each district of the plurality of districts, an actual value of an amount of grid energy which is supplied from outside of the plurality of districts to facilities inside the district, an actual value of an amount of output energy which is output from the facilities in the district, and an actual value of an amount of consumed energy which is consumed by the facilities in the district, and calculates and outputs, for the district, predicted values in a specific time slot, based on the actual values.