In Japan, many rockfall protection walls have been constructed along the nationalhighways in mountainous areas. Up till now, usually these were gravity-type walls. However, ifthere is not much space between the wall and the edge of the cliﬀ, it may not be easy to constructa normal type of wall. To rationally install the wall in these areas, a retaining wall connectedto a steel pile foundation attached to a two-layer absorbing system was recently developed.Here, in order to establish a rational design for this type of retaining wall, an impact responseanalysis was performed by means of three-dimensional elasto-plastic FE analysis. The two-layerabsorbing system used here is composed of a 15 cm thick reinforced concrete slab together with a50 cm thick expanded polystyrene (EPS) block. The retaining wall is connected to the steel pilesby inserting H-section steel members embedded in the wall. The applicability of the proposedFE analysis method was veriﬁed by comparing with the prototype impact test results.