In order to rationally design the anchoring depth of the steel posts for rockfall-protection fence embedded into the concrete retaining walls, static and drop-weight impact loading tests were conducted on H-section steel-post installed into the plain-concrete foundation model varying length of the moment arm. The results obtained from this study were as follows: 1) plastic hinge was formed in H-section post irrespective of loading type and length of moment arm; 2) the rotation angle of the H-section post after impact loading tended to be linearly increased with increasing the input energy; and 3) design values of the anchoring depth tend to underestimate referring to the experimental results.