The electron structure of the semi infinite CuO2layer has been calculated to understand peculiarities of the layered oxides surfaces. All computations have been performed by means of the Green function method along with the simple tight-binding model. Fourier transforms of the Green functions were derived analytically. The potential at the atoms nearest to the boundary was directed to infinity. This formal maneuver led to dividing the ideal CuO2layer into two semi infinite layers. The density of states near the surface has been obtained by integrating the imaginary part of the diagonal element of the Green function over the wave vector. It has been shown that the charge on the surface Cu atoms is greater than on the bulk one. Changes of the density of states via the energy and the distance from the surface have been obtained.