New loading method is proposed to evaluate an ultimate strength of radial gate arm during gate operation experimentally. In the proposed method, one wire rope and some pully blocks are attached among an experimental model of radial gate strut arms. Water pressure load is simulated by suspending a heavy mass on the wire rope. On the other hand, another wire rope is attached along an arc-like skinplate of the gate model. Gate opening is simulated by pulling the wire along the skinplate. Feasibility of the proposed method is confirmed through the experiment.