This paper describes a numerical method to solve nonlinear free surface wave problem for two-dimensional submerged bodies. The velocity potential is expressed as a sum of the basic velocity potential of double model flow and the perturbed wavy potential. The author previously showed the practical method to solve the wavy potential by using Rankine sources under the linearized free surface condition based on the double model flow. In this paper, he presents a iterative method for solving the wavy potential under the nonlinear free surface condition using the linear solution as the first approximation. The method of numerical solution is examined on the steady waves around a two-dimensional submerged elliptic cylinder and the stability of numerical solution is discussed. Further, the measurements of wave profiles and flow field beneath the free surface are carried out using the elliptic cylinder and nonlinearity of wave form are experimentally investigated. The calculations of the steady waves and velocity distribution around the elliptic cylinder are performed and good agreement with the experimental results is obtained. Finally, the simplified method for solving Rankine source distribution is proposed. It has been found from the view point of practical use that the numerical results of the simplified method agree well with that of the original method.