The techniques of structural analysis of a ship hull, namely, the theoretical estimation of ship motion and wave-induced dynamic pressure and the statistical estimation of ship responses, are generally accepted as very useful tools, and reports have been made on long term distributions of wave-induced dynamic pressure, longitudinal stresses of a ship hull, etc. in irregular seas. The authors have made an attempt at the total analyzing system on the transverse strength of an oil tanker in order to rationalize the technique of the ship structure analysis. The system involves many consistent programs concerned with ship motion, wave-induced dynamic pressure, overall structural analysis of tank part and statistics. The present papes gives an outline of the system and examples of calculation. This method will be utilized to improve initial design calculations and to make ship structures safer by introducing the knowledge gained by analysis of actual ships with this system.