Recently, South Korea has been facing a range of disasters caused by localized heavy rainfalls, tropical typhoon, and torrential downpours. In particular, debris flows disasters usually occurring in the mountains have rapidly increased during the past few years. However, debris flows are also observed in mountainous areas near cities, bringing significant damages to city centers, highways, bridges, etc. Thereby, debris flows can lead to high risk in both mountainous areas and city centers. In addition, difficulties in debris-flow forecasting increase the need for numerical studies on debris flows. Although various researches have widely been conducted on run-off control facilities for debris flows, it is necessary to focus more on research that would identify an ideal location for debris flow runoff reduction facilities based on basin characteristics or site conditions for the debris flow areas. In this regard, this research used a debris flow numerical model to identify the transfer mechanism of debris flows and analyzed the debris flow reduction effect of runoff control facilities by the installation location.