In this paper, the structural health monitoring system for “Uldolmok Tidal Current Power Pilot Plant (TCPP)” is briefly introduced and the measured data obtained up to now are analyzed. TCPP is basically constructed in the ocean area with high current speed, and therefore the current loading is governing the structural safety than the wave or wind loadings. Usually the soft soils are eroded due to the current and the soft and hard rocks are composing the seabed in strait which tidal current of high speed. Therefore the coring is not so easy due to rock seabed condition and also the operational time is very limited. And also the structural members should not be over designed with large size of steel pipe not to obstruct the tidal current. Due to the difficulties in coastal construction, relatively severe current loadings, and optimized slender structural members, it is very important to monitor the structural safety of the tidal current power plant in normal operation condition and also in severe storm condition. However, the sensor installation is much more difficult for TCPP structure than conventional in-land structures such as bridges and buildings since the sensors should be fully waterproof and the cables should be able to endure the corrosive condition. In this study, we installed the sensors under the sea level and are going to install the sensors above the sea level in this year after the construction is completed. Now the structure is under construction. The conventional type strain sensors and smart FBG optical sensors were installed in the lower part of the jacket legs to measure the dynamic and static strains and the MFC (Macro Fiber Composite) sensors were also installed at the same location to measure the impedance change due to loading and corrosion conditions.