Accidents caused by the domino effect in chemical plants or the petrochemical industry are generally more serious than any other accidents. Although the factors or mechanisms that might cause the domino effect have been studied, it is difficult to examine the true factor because the domino effect is affected by many nonlinear factors. Hence, it is almost impossible to predict the result. The immediate causes of the domino effect are the peak overpressure, flying objects, and name, and nonlinearity is inherent in all three causes. However, it is believed that a systematic and mathematical approach can minimize the incidence of the domino effect. This study considered the case where there were N-explosive facilities such as storage tanks, high temperature reactors in the given arbitrary rectangular facility site. This paper suggests the positions that can minimize the domino effect using a nonlinear approach. The well-known method of gradient or steepest descent was adopted in this work. The method initiated an arbitrary number of facilities in addition to the original position, and can search for the position to minimize the domino effect. This paper presents a new computer-aided module, MiniFFECT (MINImization of domino eFFECT), which can simulate the procedure for deciding the position of N-facilities for minimizing the domino effect.