There are large number of dangerous slopes in Japan because of geographical, geological and climate conditions. Due to the limitation of the budget, it is impossible to carry out disaster-prevention measures for all dangerous slopes. Therefore, it is necessary to propose an efficient screening technique to extract high-risk slopes. This study presents a method for evaluation of discontinuous rock slope. Main features of this method are as follows; 1) stability of triangular pyramid and wedge shaped blocks can be evaluated; 2) three modes of failure, i.e. rockslide, rockfall and toppling are taken into account; 3) stability analysis is based on limit equilibrium theory; 4) friction angle, cohesion and tensile strength of joint are taken into account; 5) pore-water pressure and seismic force can be applied to the block; and 6) conditions of stability blocks are evaluated with simplified vector formulas. The proposed method is applied to the practical design for a cut slope in Gifu prefecture, Japan. The reduction in the shear strength of discontinuous planes due to weathering and stress release is taken into account. The rockbolt system as the countermeasure is employed based on the stability analysis.