Predictive model evaluation means 81 evaluates closeness in property between a relearned predictive model and a pre-relearning predictive model. Predictive model updating means 82 updates the pre-relearning predictive model with the relearned predictive model, in the case where the closeness in property meets closeness prescribed by a predetermined condition. The predictive model evaluation means 81 evaluates closeness in prediction result or structural closeness, as the closeness in property of the predictive model.