This paper presents the numerical procedure for solving the fluid-structure interactive vibration of a three dimensional complicated structure such as the stiffened plate, deep girder, transverse ring and so on. So far, a classical boundary element method has been widely used for estimating the added mass effect. of the fluid surrounding the structure. However, when the plate thickness is relatively thin, the previous method may not. be applicable because the numerical error is not neglected to evaluate the fluid loading effect. on the plate. Thus, a new program code TPBEM is developed and applied to determine the distribution of the dynamic pressure on the thin circular plate and the web frame model. Some of the calculated results are compared with measured ones and the validity of the present. method is discussed.