An energy operation support device comprising: a result value/prediction value acquisition unit configured to acquire result values of a generation amount and a consumption amount of an energy utility at a current time and prediction values of the generation amount and the consumption amount of the energy utility from the current time to a designated time for each factory configuring a steel works; a unit price information acquisition unit configured to acquire unit price information required for calculating a total cost for an energy operation of the steel works; a functioning information acquisition unit configured to acquire functioning information of an energy facility of the steel works; an optimization calculation unit configured to, based on information obtained from the result value/prediction value acquisition unit, the unit price information acquisition unit, and the functioning information acquisition unit, set an operation condition of the energy facility as a determination variable, constitute a balance condition of the energy utility, add an shortage amount determination variable of the energy utility to a generation variable side of the balance condition and establish a constraint condition, set an objective function containing the total cost for the energy operation of the steel works and the shortage amount determination variable, and arithmetically operate the determination variable such that the objective function asymptotically approaches an optimum value to satisfy the constraint condition; and an operation guideline transmission unit configured to transmit an operation guideline to an operator based on the shortage amount arithmetically operated in the optimization calculation unit. a result value/prediction value acquisition unit configured to acquire result values of a generation amount and a consumption amount of an energy utility at a current time and prediction values of the generation amount and the consumption amount of the energy utility from the current time to a designated time for each factory configuring a steel works; a unit price information acquisition unit configured to acquire unit price information required for calculating a total cost for an energy operation of the steel works; a functioning information acquisition unit configured to acquire functioning information of an energy facility of the steel works; an optimization calculation unit configured to, based on information obtained from the result value/prediction value acquisition unit, the unit price information acquisition unit, and the functioning information acquisition unit, set an operation condition of the energy facility as a determination variable, constitute a balance condition of the energy utility, add an shortage amount determination variable of the energy utility to a generation variable side of the balance condition and establish a constraint condition, set an objective function containing the total cost for the energy operation of the steel works and the shortage amount determination variable, and arithmetically operate the determination variable such that the objective function asymptotically approaches an optimum value to satisfy the constraint condition; and an operation guideline transmission unit configured to transmit an operation guideline to an operator based on the shortage amount arithmetically operated in the optimization calculation unit.