Abstract
　A landslide at a site beside the prefectural road connecting Otsu and Shigaraki, Shiga Prefecture Japan resulted in the death of two persons. According to a post-disaster inspection, the landslide involved a translational sliding of a V-shaped block, toppling and fall. These movements are thought to have been controlled by the joint system in the granite which composed the slope. A dynamical analysis of the destruction of steel pillars which had supported the protective fence reveals the velocity of debris and suggests the mechanism of the slope failure. Discussion covers the predictability of such roadside hazards and the possible countermeasures. Considering a wide variation in the mode of roadside slope failures, importance of studies of the causes for individual cases is emphasized in conclusion.

【キーワード】：道路災害，崩落，トップリング，基岩すべり，予測
Key words: road hazard, landslide toppling, rockslide, prediction

*京都大学防災研究所
Disaster Prevention Research Institute, Kyoto University