The slope failure induced by Hiroshima heavy rainfall on June 29，1999 took many human lives，ravaged houses，and brought great damage. Then，the disaster reminded us of the fact that slope failure may happen at any time. One of the important factors seems to be the amount of deposit soil of weathering granite soil. First，geotechnical engineering maps of the area were made based on the results of the multiple regression analysis，and the ground database was made on the satellite“ADEOS" data. Furthermore，the weathering classification data was used as the disaster information data found in subsurface geology map. We also tried to predict the amount of collapse soil on a natural slope and the amount of product soil at the time of the disaster by applying End area formula using longitudinal and cross section of the watercourse of the area.