Investigation on latency disaster is useful to get the information of place, scale, and distribution above the sediment disaster. Plan on sediment disaster prevention is attend to avoid sediment disaster area occurred in the place mentioned above where the control work build. The items of environment factor, the place and scale of sediment disaster are suggested by investigation of the study. The amount of activity and the influence area of sediment disaster are obtained by the procedure of theory analysis, aero photo judgment, and field investigations. After that planning on control work and disaster prevention are performed by this result.