In obtaining the hydrodynamic pressure exerting on the ship's hull running in regular waves, the Ordinary Strip Method has been used so far. However, the Strict Strip Method has recently been proposed by Nakamura and Takagi. In this new method, unlike the O. S. M., the wave-induced hydrodynamic pressure can be obtained from the direct solution of the diffraction problem by satisfying the boundary condition on the surface of the ship. In the present paper, descriptions are made on the experiments which were conducted to see what is the practical accuracy of estimation of the hydrodynamic pressure in the above two calculation methods. Measurements were made not only for the total hydrodynamic pressure, but also for two kinds of pressure components ; wave-induced and radiation pressure, and comparisons of these pressures were made between the calculated values and the experimental ones. From the present study, it is shown that the above two strip methods are useful and they give the accuracy of estimation with almost the same order. Both methods, however, will be much more useful for obtaining the hydrodynamic pressure, if the ship's rolling motion could be estimated more accurately.