Shell-typed structures can make resistance to external forces efficiently, and have merits to construct the large-span structures with thin thickness. This merits are highly depending on the shape of structure. Therefore designers want to the optimum shape, but it is not so easy to find the shape. So far there are many schemes to find more optimum shape, and those methods have their own characteristics. In this study, the authors introduce a relatively easy approach to find optimum shape by the finite element method considering geometric nonlinearity. We are finding the optimum shape of a shell-typed structure using line elements, and compared the results by various analytic models.