- - - Department of Mathematics, University ۸ May ۱۹۴۵ Guelma, Algeria

In this paper we will study the existence, uniqueness and positivity of solution of a boundary value problem for nonlinear fractional differential equation, by using Leray-Schauder nonlinear alternative, Banach contraction and Guo-Krasnosel'skii fixed point theorems.

Fractional differential equations, Fixed point theorem, Guo-Krasnosel'skii theorem, Leray-Schauder nonlinear alternative, Banach contraction theorem, Existence, uniqueness, positive solution