In this paper, the large deflection problem of a circular plate subjected to internal pressure is treated. In-plane tension is acting before subjecting the pressure loading. In the deformation analysis of the circular plate, simultaneous nonlinear differential equation system is derived by applying the von Karrman's large deflection theory. The circular plate is clamped or simply supported at the boundary edge. At the finite element method formulation, the Galerkin method that is a kind of weighted residual method is applied. By numerical calculation, the present solution is compared with the solutions obtained from linear theory and the Heckey's membrane theory. Furthermore, it is also shown that the present solution approaches to the membrane solution for large values of a pressure parameter.