An OLED display device and a method of fabricating the same. The OLED display device has at least one of a common power bus line or a cathode bus line formed at a peripheral portion of the OLED display device. By forming a lower line when a gate electrode of a thin film transistor is formed, and forming an upper line connected to the lower line through a contact hole when source and drain electrodes of the thin film transistor are formed, a dual structure of lower and upper lines is formed. As such, the OLED display device can reduce the width of interconnections without a high voltage drop to thereby increase an emission area of a light emitting portion of the OLED display device.