Gangwon Province in Korea is relatively vulnerable to landslides and debris flows since it is mountainous and has a climatic condition under which summer monsoon and localized heavy rain occur frequently. Scale generation of flash floods and debris flow become greater in the case of cumulative rainfall, causing a greater scale of damage. As it is critical to identify a threshold of rainfall amount triggering flash food, debris flows and landslide, this study develops a flash flood-triggering rainfall curve and a debris flow-triggering rainfall curve. Debris flows and landslides caused by rainfall were estimated as rainfall intensity, both effective average rainfall and accumulated rainfall, depending on the effective time. In order to estimate the amount of flash flood-triggering rainfall, we estimated peak discharge, overtopping discharge, and threshold runoff. As a result, by making a linkage between the flash flood-triggering rainfall and the debris flow-triggering rainfall, we presented the two rainfall regression curves, FADG (Flash flood and Debris flow Guidance) curves for flash flood and debris flow, as a tool to monitor triggering rainfall.