An organic light emitting device according to embodiment of the present invention comprises: a substrate; a first electrode formed on the substrate; a light-emitting member formed on the first electrode, and comprising multi-layer structure; and a second electrode formed on the light-emitting member, wherein the second electrode comprises Mg--Ag alloy which contains Mg of 1-10 wt % and a concentration gradient of the Mg--Ag alloy is formed from the top of the emitting-light member.