The method of auxiliary mapping (MAM), introduced by Babuška and Oh, was proven to be very successful in dealing with monotone singularities arising in two-dimensional problems. In this article, in the framework of the p-version of FEM, MAM is presented for one-dimensional elliptic boundary value problems containing singularities. Moreover, in order to show the effectiveness of MAM, a detailed proof of an error estimate is also presented, which gives a sharp error bound of MAM.