It is well known that the strip method is a calculating method of pitch and heave of ships in regular waves, and the calculated results show fairly good coincidences with the experimental results in general ship forms, but are not in special ship forms and in high speed range. The author studies this method and gets some results. There are two processes of calculating pitch and heave of ships. One is to get a hydrodynamical property (singularity distributions) of a ship form, and the other is to get hydrodynamic forces from the former. In the strip method the forces acting on a ship hull are got by summing up the two-dimensional forces acting on a.strip, so this method is one method of the later process and it is free for the former process. On the former process, starting from the thin ship theory, he gets the velocity on the bottom different from that being obtained by the ordinary strip method, and he introduces numerical formulae. By this new formulae we can obtain the effect due to an advance speed. Pitch and heave of some ships are calculated by the two methods, and their results are compared each other. By the new method, amplitudes of heave are less than by the ordinary method, but amplitudes of pitch are larger. There are better agreements with experimental results on amplitudes of pitch and heave by the new method than by the ordinary method, but are some differences on phase lags. The influences of velocity distributions on a ship hull are examined but they are small.