This paper proposes a valuable road hazard map against falls and failures of discontinuous rock slopes from the practical engineering viewpoint, which makes it possible not only to evaluate risk of rock block fallings and slidings but also to predict the arrival length along a falling path of dangerous rock slope. This road hazard map may be obtained from the simulation analyses of Distinct Element Method based on some useful parameters determined from the proof tests of actual rock block fallings. This proposed map is effective to comprehensively consider the degree of road safety against fallings and failures of rock blocks. Therefore, it becomes easy from it to decide both the preferential construction positions of protected structures as the hard measure aspect and the needful sections of road traffic control as the soft measure aspect.