The organic light emitting display device includes a substrate including a thin film transistor (TFT) formed thereon, the TFT including a first insulating layer disposed between an active layer and a gate electrode, and a second insulating layer disposed between the gate electrode and source and drain electrodes; a pad electrode including a first pad layer disposed on a same layer as that where the source and drain electrodes are formed, and a second pad layer on the first pad layer; a bonding assistant layer on the substrate; a third insulating layer on the bonding assistant layer and including a first opening; a pixel electrode disposed in the first opening and electrically coupled to one of the source and drain electrodes; and a fourth insulating layer on the pixel electrode to cover a peripheral end portion of the pixel electrode and defining a pixel through a second opening.