The purpose of the present invention is to calculate the flow volume per unit time of fuel fed into a gas turbine, and to calculate the flow volume per unit time of air fed into the gas turbine. A turbine entry temperature is calculated using a physical model formula expressing the relationship between the input and output of heat energy relating to a combustor of the gas turbine. A fuel allocation ratio for each of a plurality of fuel supply systems connected to the combustor is calculated on the basis of the turbine entry temperature.