In this paper, the applicability of structural health monitoring (SHM) system is evaluated on a full-scale concrete cable-stayed bridge, Hwamyung Bridge in Korea. Firstly, Imote2-platformed wireless sensor node for structural health monitoring is designed to monitor the cable forces by the vibration-impedance-based SHM. Secondly, the experimental setup is presented by filed verification test on Hwamyung Bridge. Finally, the long-term monitoring performance of the wireless sensor system is examined under various weather conditions. Also, the accuracy of cable force monitoring by the wireless sensor system is evaluated for the target bridge.