In this paper the pressure distributions on partially cavitating three dimensional wings are calculated and measured. In calculating the pressure distribution Hanaoka's linearised lifting-line. theory has been developed and the coupled integral equations have been practically solved for the elliptical and the rectangular wing with the circular ogival profile. In addition, the iterative. method for calculation of lifting-surface using Prandtl's lifting-line theory has been improved and satisfactory agreements with the calculated results by the existing lifting-surface theory are; obtained. Numerical results for the pressure distribution on the sub-cavitating finite wings can explain well the experimental results. And the result that the calculated values of derivative of cavity profiles are nearly zero is found independently of the given shape of the planform of finite wings. The advantage of this method over the other specious method lies in its ability to estimate the pressure distribution, cavity profile and lift coefficient etc. theoretically.