We propose a new network collaboration system, named DIGA (Distributed Interactive Genetic Algorithm), where IGA is extended to Parallel and Distributed Model. By using DIGA we can realize an IGA-based design system with many people at the same time. DIGA is aimed to solve problems of making creative plans and making agreement within a group. We developed a proto-type system and applied the proposed approach to make good plans for selecting the colors of three furniture (sofa, curtain, and carpet). The experiment shows the effectiveness of the method.