A new constructive method for the finite-difference solution of the Laplace equation with the integral boundary condition is proposed and justified. In this method, the approximate solution of the given problem is defined as a sequence of 9-point solutions of the local Dirichlet problems. It is proved that when the exact solution u(x, y) belongs to the Hölder calsses C 4,λ , 0 < λ < 1, on the closed solution domain, the uniform estimate of the error of the approximate solution is of order O(h 4 ), where h is the mesh step. Numerical experiments are given to support analysis made.