An organic light emitting display device comprising: a data driver supplying data signals to data output lines; a scan driver supplying scan signals sequentially to scan output lines; a light emitting control line driver supplying light emitting control signals to light emitting control output lines; and a pixel unit including a plurality of pixels connected to the output lines of each driver, at least one driver having a buffer circuit disposed at each output line. Each buffer circuit comprises a transistor having a gate layer, source and drain layers and a metal layer for shielding Electro-Static Discharge (ESD), wherein the metal layer is formed over the gate layer when the gate layer is overlapped by one of the source or a drain electrodes, or the metal layer is formed to not overlap the gate layer when the gate layer is not overlapped by the source or a drain electrodes.