The amplitude functions measured by wave analysis experiment for a ship model are expanded in Mathieu function series in order to obtain the informations of improving the hull form. The expansion gives sectional area curve of the model as assumed as a source generating the measured wave system in linear wave-making theory. The expansion coefficients correspond with the coefficients of Mathieu expansion of the assumed sectional area curve and give the strengths of wave pattern resistance components. In order to reduce the total wave resistance the sectional area curve components corresponding with the dominant wave resistance components is to be subtracted. The amplitude functions measured for three ship models are expanded in Mathieu function series and their wave resistance components are compared with each other at various Froude numbers. The direction of improving hull form obtained by the present method corresponds with the design philosophy of the three ship forms.