An organic light emitting display device and a method of fabricating the same are provided, which employ an Ag alloy containing Sm, Tb, Au, and Cu to simultaneously form a source electrode, a drain electrode, and a first electrode of the organic light emitting display device for increasing the reflectivity and efficiency of the organic light emitting display device and reducing the organic light emitting display device panel size by reducing a line width of the source and drain electrodes due to the low resistance of the source and drain electrodes.