In this paper, we illustrate a decision support system of modeling the room designs suited for personal preference. The preference to colors is differed to individual personality. Nevertheless, modeling the room design is depended on the designer's sensitivity until now. Therefore, the technique of modeling the various room designs people satisfy is needed. In this paper, we propose automatic modeling system of the room design using interactive genetic algorithm (IGA). IGA has the advantage of learning the user's interactive evaluation, which is applied to the production of new room designs suited for the personal preference. The proposed system can help a decision support of modeling the various room designs, and reduce the burdens of designers significantly. In proposed system, the design evolution of IGA can reflect the user preference, and we present the effectiveness of the system by simulations.