Abstract: We study numerical methods for the exterior problems of the Helmholtz equations. It is known that the spectrum of the Laplace operator is continuous and the boundary value problem is uniquely solvable under the Sommerfeld radiation condition. Various methods have been given for the numerical computation to these problems. Here we introduce a new approach to the infinite element method, which enables us to solve scattering problems with large wave numbers. We will present the analysis of this method and show a numerical example for three dimensional scattering problems.