The main cause of the Hiroshima disaster Junc 1999 is the heavy rain due to the cold front. This heavy rain appeared in the band with small width. It was considered that this concentration of rainfall was under the influence of the mountainous geographical features and the wind fields. A radar rain gauge was effective to know the distribution and the movement of this heavy rain, if we use the ground rain gauge together. It is considered that the radar rain gauge system is effective for short time prediction of rainfall through the movement of heavy rainfall area. We examine the feasibility of simple prediction of rainfall based on the radar rainfall gauge. As the result, it is necessary to consider the change in rainfall due to the mountainous geographical features.