Dynamic behavior of RC beam under single impact loading has been studied by many researchers in recent years. However some RC protective structures such as RC caisson breakwater wall are subjected to not only single impact but also repeated impact loading in in-service period. So, it is important to clarify the damage condition of RC member under repeated impact loading. We have studied cumulative damage of RC beam under repeated impact loading by using numerical technique. In that previous study, to evaluate the damage condition and residual performance of RC beam under repeated impact loading, we have proposed the evaluation method of residual performance based on cumulative damage models. As a result, it is found that the cumulative damage and residual displacement of RC beam could be properly evaluated by using our proposed method. Although our proposed method has been verified for RC beam under repeated impact loading, the validity and accuracy for RC slab have not been thoroughly studied. The main objective of this study is to quantitatively evaluate the dynamic behavior, the impact failure mechanism and the residual performance of RC slab subjected to repeated impact loading. From the viewpoint of the impact-resisting design of RC caisson breakwater wall covered with wave-dissipating blocks, at first, structural behavior and damage distribution of the RC slabs subjected to repeated impact loads were investigated through falling weight impact loading tests. Second, numerical approaches for damage evaluation of RC slab under single and repeated impact loading (low velocity impact) were conducted by using proposed method.