The actual performance information classify part derives a classification result of an actual performance information on electric power demand, by a classification setting information, from an environment information and a date attribute information which is correlated with each of the electric power demands which is included in an actual performance information on electric power demand. The prediction information calculate part derives a classification result of a prediction target day, using the date attribute information of the prediction target day, which is a day to conduct a prediction, and the environment information which is measured before a start of the prediction of a prediction target day, and in addition, predicts an electric power demand of a prediction target day, based on the electric power demand of the actual performance information on electric power demand, which corresponds to the classification result of the prediction target day.