In this paper, a three-dimensional elasto-plastic response analysis on impact loading tests of a full-scale conventional rockfall protection fence was performed, and the applicability of the proposed analysis method was verified by comparing with the experimental results. Furthermore, using the proposed method, a parametric study was conducted to investigate effects of the magnitude of diameter of the falling rock and number of spans on dynamic behavior of the fence under the condition of the same impact energy. The results obtained from this study were as follows: 1) time histories of the dynamic responses can be appropriately estimated by using the proposed method; and 2) effects of the mass of the falling rock and number of spans were numerically clarified.