Linearized theories on a supercavitating hydrofoil are not suitable for the foil with a rounded nose where a sheet cavity does not generate from the leading edge of the foil. The theoretical result gives a negative infinite pressure at the leading edge because of singularity. Furuya proposed a new theoretical method to remove the singularity by applying the singular perturbation method. But it can not give a definite position of cavity tip for a given cavity end. Developing Furuya's theory, the authors propose a new iterative method in which the position of cavity tip agrees with the laminar separation point. Cavitation experiment was made for a hydrofoil with parabolic section. The test result was modified to remove wall effects of tunnel, using a newly developed method by the authors. The calculated results by the proposed theory agreed with the experimental results on the pressure distribution as well as the cavity shape.