Abstract: Based on the comparison of experimental results between silica sands and soil samples taken from rapid landslide sites, by means of triaxial tests and ring shear tests, the mechanism of rapid landslides is analyzed,and a model for changing apparent friction coefficient during landslide motion is proposed. Substituting this model into the kinematic equation and continuity equation of landslide motion proposed by Sassa(1998),the calculus of finite difference procedure for prediction of landslide motion is extended. Through a case study on Sumikawa landslide, the argument of the prediction method is supported.