“…Then for each given element x ∈ X, either d(J n x, J n+1 x) = ∞ for all nonnegative integers n or there exists a positive integer n 0 such that (1) d(J n x, J n+1 x) < ∞, ∀n ≥ n 0 ; (2) the sequence {J n x} converges to a fixed point y * of J; (3) y * is the unique fixed point of J in the set Y = {y ∈ X | d(J n 0 x, y) < ∞}; (4) d(y, y * ) ≤ In 1996, Isac and Rassias [20] were the first to provide applications of stability theory of functional equations for the proof of new fixed point theorems with applications. By using fixed point methods, the stability problems of several functional equations have been extensively investigated by a number of authors (see [21][22][23][24][25]). This paper is organized as follows: In Sections 2 and 3, we prove the Hyers-Ulam stability of the following bi-additive s-functional inequalities…”