In this study, fine particle distribution in artificial slopes comprising weathered granite, which may affect rainfall-triggered landslide, was investigated comprehensively, based on electrical resistivity, soil composition and unsaturated soil properties. The results showed that while degree of saturation plays a key factor on electrical resistivity in unsaturated soil, it has close correlation to pore-size distribution. Therefore, it can be considered that electrical prospecting is an effective method to investigate distribution of both coarse particle and fine particle. In addition, it was also pointed out that there is possibility that fine particle fraction involved in soil poorly compacted in artificial slopes may be eroded due to rainfall infiltration.