An organic TFT that has an improved contact between source and drain electrodes and an organic semiconductor layer, a method of manufacturing the same, and an organic light emitting display device having the organic TFT are disclosed. The organic TFT includes a substrate, a gate electrode disposed on the substrate, a gate insulating film covering the gate electrode, a source electrode and a drain electrode disposed on the gate insulating film, a peel-off preventive layer disposed on the gate insulating film to contact at least a portion of end surfaces of the source and drain electrodes, and an organic semiconductor layer that contacts the source and drain electrodes.