Factors affecting the frequency of occurrence of cracks (number / km) on roads paved with asphalt around Matsue City were discussed through field investigations. Results show that the frequency varies with the types of rocks. Many cracks are found in the andesite beds of the Miocene Omori Formation (8.3 / km), siltstone in the Miocene Furue Formation (7.7 /km) and mudstone in the Miocene Josoji Formation (7.5 /km). On the other hand, the rocks with low frequency are sandstone in the Miocene Fujina Formation (1.6 / km), Eocene Hiyodori granite (3.4 / km) and conglomerate in the Miocene Koura Formation (3.6 /km). The frequency is higher on dip slope than opposite slope. The frequency increases as the slope angle around the roads increases. The frequency sharply increases when the slope angle exceeds 25 degrees in the andesite beds in the Omori Formation and Hiyodori granite, showing a similar trend, as is shown in the relationship between the frequency of occurrence of slope failure and slope angle.