Based on the finding that the wave-making resistance of a slow speed full ship depends solely on the shape of entrance provided the hull form is designed properly, a new method of designing hull form of large full ship is presented. The method consists of the following processes : (1) The proper shape of run is selected taking the design requirements such as propeller arrangement, prevention of flow separation, etc. into considerations. (2) Then the optimum entrance shape is determined for the value of C _m H _e/ B which is determined from the given conditions on principal dimensions. (3) Estimating the form factor and the self-propulsion factors for the such determined ship form, the total resistance and SHP can be calculated. Therefore, the optimum hull form with the minimum SHP for the given design conditions can be easily designed. This method was developed by the authors in Mitsubishi Experimental Tank (Nagasaki) and has been applied to the practical design work resulting in a remarkable accomplishment of economical hull forms.