The present invention relates to a light emitting diode having an AlxGa1-xN buffer layer and a method of fabricating the same, and more particularly, to a light emitting diode having an AlxGa1-xN buffer layer, wherein between a substrate and a GaN-based semiconductor layer, the Al x Ga 1-x N (O≦x≦1) buffer layer having the composition ratio x of Al decreasing from the substrate to the GaN-based semiconductor layer is interposed to reduce lattice mismatch between the substrate and the GaN-based semiconductor layer, and a method of fabricating the same. To this end, the present invention provides a light emitting diode comprising a substrate; a first conductive semiconductor layer positioned on the substrate; and an AlxGa1-xN (O≦x≦1) buffer layer interposed between the substrate and the first conductive semiconductor layer and having a composition ratio x of Al decreasing from the substrate to the first conductive semiconductor layer.