We introduce the Interactive Modeling Support System (IMSS) that is a highly user-friendly software to develop mathematical models in systems analytic research. The system IMSS utilizes graphical information effectively to facilitate not only human-computer communication but also interpersonal communication. As an application of using IMSS, we present the process of identifying an environmental prediction model. It is emphasized that IMSS greatly reduces the burden of trial and errors necessary in developing such a model, and helps us think about the problem systematically and intensively.