A thin film transistor and a method of fabricating the same capable of reducing stress of a substrate caused by a metal layer of the drain and source electrodes, the thin film transistor including a substrate; a semiconductor layer disposed on the substrate and including source, drain and channel regions; a gate insulating layer disposed on the substrate including the semiconductor layer; a gate electrode disposed on the gate insulating layer to correspond to the channel region of the semiconductor layer; an interlayer insulating layer disposed on the substrate including the gate electrode, and having contact holes connected with the source and drain regions of the semiconductor layer; and source and drain electrodes connected with the source and drain regions through the contact holes, wherein the source and drain electrodes include a first metal layer, a second metal layer, and a metal oxide layer interposed between the first metal layer and the second metal layer. Accordingly, the thin film transistor can reduce stress of the substrate caused by a metal layer of the source and drain electrodes, thereby improving yield of an organic light emitting diode display device.