The strip method is generally used to calculate pitch and heave of ships in regular waves, but this method is not the perfect method. The author has already obtained the vertical component of flow velocity by applying the thin ship theory, in this report, however, he also shows the vertical component will be determined by the slender ship theory different from the strip method. He obtained, furthermore, the new formulae of calculating pitch and heave of ships by the strip method, using the vertical component 'obtained above with the Takagi's method. By using four methods, such as Watanabe's (ordinary), modified Watanabe's, Takagi's or modified Takagi's method, the pitch and heave of several ships are numerically obtained and compared each other. Comparison between the new method and the ordinary method shows that maximum amplitudes of heave obtained by the new method become generally less than those by the ordinary method, and maximum amplitudes of pitch become larger in the former than those of the latter.