A Thin Film Transistor (TFT) includes: an active layer including a channel region, a source region, and a drain region; a gate electrode insulated from the active layer and adapted to supply a signal to the channel region; and a source electrode and a drain electrode, insulated from the gate electrode, and adapted to be connected to the source and drain regions, respectively, the source and drain electrodes including a first metal layer pattern and a second metal layer pattern, the first metal layer pattern adapted to be in contact with the source and drain regions of the active layer and containing at least one metal selected from the group consisting of Cr, Cr alloys, Mo, and Mo alloys, and the second metal layer pattern being arranged on the first metal layer pattern and containing at least one metal selected from the group consisting of Ti, Ti alloys, Ta, and Ta alloys; wherein the first metal layer pattern has a thickness of 500 Å or less. The TFT has a low interconnection resistance of source/drain electrodes, prevents contamination from an active layer, has improved contact resistance with a pixel electrode, and facilitates the supply of hydrogen to the active layer to improve mobility, on-current, and threshold current. The thickness of a molybdenum alloy-based layer of source/drain electrodes is controlled to provide better uniformity.