It is said that the influence of the permanent deformation characteristics of subgrade materials on the development of rutting in lightly trafficked asphalt pavements is larger than that in heavily trafficked ones. In this study, relationships among cohesion ©, angle of internal fiction (?) and CBR of a subgrade material were obtained by tri-axial compression test and the CBR test. Then rutting simulations of lightly trafficked asphalt pavements designed by the CBR method were carried out using the elasto-plastic model for cycling loading based on the modified Cam-clay model. As a result, it was found that the depth of rutting increases with CRB of the subgrades, because thickness of each pavement structure yields higher stresses at the top of the subgrade due to traffic loading and generates large plastics deformations in the subgrade leading to deep rutting at the pavement surface