Disclosed are a solar cell and a method of fabricating the solar cell. The solar cell includes a back electrode layer; a light absorbing layer on the back electrode layer; and a buffer layer on the light absorbing layer, wherein the buffer layer includes a first buffer layer, a second buffer layer on the first buffer layer and a third buffer layer on the second buffer layer, and wherein the first buffer layer includes a group I-VI compound. A method of fabricating a solar cell includes the steps of: forming a back electrode layer on a substrate; forming a light absorbing layer on the back electrode layer; forming a second buffer layer on the light absorbing layer including selenium; and forming a third buffer layer including sulfide on the second buffer layer.