PROBLEM TO BE SOLVED : To support real estate purchase decision making when a plurality of real estates exist on the basis of a market trend observed by a user, qualitative situations of economic environment, etc., and quantitative conditions such as user' s budget with them as factors.SOLUTION : A qualitative reasoning mechanism 11 and a quantitative calculation mechanism 12 ascertain tendency of future factors. Qualitative information and quantitative information obtained by this predicting method are integrated, a determination result processing part 14 determines decision making on the basis of conditions such as a budget, and decision making of real estate purchase can be supported when a plurality of real estates exist.