The purpose of this paper is to formulate and apply the stability analysis of toppling failure by considering the variation of discontinuity characteristics, slope geometry, and loading conditions. The stability condition on toppling failure of rock slope is mainly iuluenced by the dip angle $alpha_B$ and H/t ratio. In order to check toppling failures in design, the stability charts composed of dip angle $alpha_B$ versus H/t ratio have been constructed in the paper. In general, smaller dip angle $alpha_B$ and smaller dip angle $alpha_B$ and smaller H/T ratio give safer condition. The suggested curves change rapidly at the chitical point around the sone, H/t=4~6. The stable zone in stability charles becomes smaller due to step angle $data$.