Due to global warming, the need to secure an alternative clean energy resource has become an international issue. Tidal current power is now recognized as one of the clean power resources in Korea, where there are many strong current regions on the west and south coasts. Recently, large scale tidal devices have been deployed with a maximum rotor diameter of 18 m. These devices impose significant loading on supporting structures. In many cases, a pile fixed foundation is used to secure the structure. However, due to the high density of seawater, the drag and lift forces are much larger than in air, causing extensive stress and deflection to the pile tower structure. In this study, a numerical analysis of the hydro-forces from a rotating tidal current turbine to a tower was conducted to determine the deformation distribution along the pile tower.