An energy management system comprising: a collector configured to collect information regarding energy efficiency of a production apparatus; and a processor configured to perform at least one of monitoring, simulation, and optimization of energy efficiency in production activity performed by the production apparatus, on the basis of the information regarding energy efficiency collected by the collector, using a modeling unit in which information regarding energy efficiency of a constituent element of the production apparatus is modeled on the basis of a predefined rule, wherein the modeling unit comprises, as attributes indicating a feature or a state of the modeling unit, at least one selected from the group consisting of an input attribute relating to input to the modeling unit, an output attribute related to output from the modeling unit, and a consumption attribute related to consumption between input to and output from the modeling unit, the modeling unit comprises, as the attributes indicating the feature and the state of the modeling unit, at least one selected from the group consisting of an attribute group including an input attribute, an output attribute, and a consumption attribute related to a substance flow, and at least one selected from the group consisting of an attribute group including an input attribute, an output attribute, and a consumption attribute related to an energy flow, and the modeling unit comprises, as the attributes indicating the feature and the state of the modeling unit, an accumulation attribute related to a substance flow, including information indicating an accumulation amount of substance related to a difference between an inflow amount of substance which is input to the modeling unit and an outflow amount of substance which is output from the modeling unit, and an accumulation attribute related to an energy flow, including information indicating an accumulation amount of energy representing a difference between an inflow amount of energy which is input to the modeling unit and an outflow amount of energy which is output from the modeling unit. a collector configured to collect information regarding energy efficiency of a production apparatus; and a processor configured to perform at least one of monitoring, simulation, and optimization of energy efficiency in production activity performed by the production apparatus, on the basis of the information regarding energy efficiency collected by the collector, using a modeling unit in which information regarding energy efficiency of a constituent element of the production apparatus is modeled on the basis of a predefined rule, wherein the modeling unit comprises, as attributes indicating a feature or a state of the modeling unit, at least one selected from the group consisting of an input attribute relating to input to the modeling unit, an output attribute related to output from the modeling unit, and a consumption attribute related to consumption between input to and output from the modeling unit, the modeling unit comprises, as the attributes indicating the feature and the state of the modeling unit, at least one selected from the group consisting of an attribute group including an input attribute, an output attribute, and a consumption attribute related to a substance flow, and at least one selected from the group consisting of an attribute group including an input attribute, an output attribute, and a consumption attribute related to an energy flow, and the modeling unit comprises, as the attributes indicating the feature and the state of the modeling unit, an accumulation attribute related to a substance flow, including information indicating an accumulation amount of substance related to a difference between an inflow amount of substance which is input to the modeling unit and an outflow amount of substance which is output from the modeling unit, and an accumulation attribute related to an energy flow, including information indicating an accumulation amount of energy representing a difference between an inflow amount of energy which is input to the modeling unit and an outflow amount of energy which is output from the modeling unit.