In this study, in order to investigate the installing effects of space keeping members for conventional rockfall protection fences, the falling weight impact tests and 3D elasto-plastic impact response analyses were conducted taking an interval of space keeping members and falling height of the weight as variables. The results obtained from this study were as follows: 1) impact resistant capacity of the fences with space keeping members may be two times bigger than that of without the member; and 2) the tension forces applied into the wire ropes and the deflection configuration of the wire net can be roughly simulated by means of the proposed numerical analysis method.