Provided is a plant operation support apparatus including a plant simulator, a predictor, and a predicted KPI deriver. The plant simulator simulates a state at a current time or a predetermined time of a plant based on information obtained from the plant, to output an estimated value at the current time or the predetermined time of process data in the plant. The predictor predicts a state at a predetermined future time of the plant based on the estimated value and outputs a predicted value of the process data in the plant. The predicted KPI deriver derives a predicted KPI which is an index for monitoring the state at the future time of a task to be monitored in plant operation based on the predicted value.