For a finite dimensional complex Lie algebra, its index is the minimal dimension of stabilizers for the coadjoint action. A famous conjecture due to A.G. Elashvili says that the index of the centralizer of an element of a reductive Lie algebra is equal to the rank. That conjecture caught attention of several Lie theorists for years. It reduces to the case of nilpotent elements. D.I. Panyushev proved the conjecture for some classes of nilpotent elements (e.g. regular, subregular and spherical nilpotent elements). More recently, the conjecture has been proven for the classical Lie algebras by O. Yakimova and checked with a computer programme for the exceptional ones by W.A. DeGraaf. In this paper we give an almost general proof of that conjecture.