The authors had done theoretical analysis of the vibration of rectangular elastic plates in contact with water. In this analysis, using the elliptic cylindrical coordinate system, they investigated the effects of mass density ratios, chord-length to thickness ratios, aspect ratios, boundary conditions and mode shapes on the added mass of plates. The results are reported in papers quoted as the reference [4] and [5] of this paper. In this report the results of experiments conducted to verify the above theoretical analysis are presented. It shows that numerical results derived from the theoretical analysis are generally in good agreement with the experimental results.