A power generation facility operation device includes an opportunity loss calculator for calculating a power generation opportunity loss value, (a loss value resulting from losing the power generation opportunity when output of the power generated from a power generation facility is reduced according to a request for provision of reserve power desired by an electric power provider), a reserve power incentive calculator for calculating a reserve power incentive value, (a value equivalent to an incentive obtained by the electric power producer from the electric power provider by output control being performed in the power generation facility and the reserve power being supplied to the electric power provider, and a reserve power plan calculator for calculating a plan of the reserve power that the power generation facility is to secure in order to keep the power generation opportunity loss value below the reserve power incentive value.