An organic light emitting diode (OLED) display device and a fabrication method thereof are provided. In the OLED display device, when an existing power wiring using a metal used for a data wiring is divided based on a common electrode marginal region as a boundary so as to be used as a wiring as well as as the power wiring, the reduced width of the wiring is compensated for by increasing the thickness of the wiring by using a metal for an anode or a cathode, thus reducing the left and right bezel widths.