a flat panel display device is disclosed that may include a light - emitting layer portion including a first electrode , a second electrode , and an organic light - emitting layer between the first and second electrodes ; at least two thin film transistors for controlling the light - emitting layer portion ; a scanning signal line for supplying a scanning signal to the thin film transistor ; a data signal line for supplying a data signal to the thin film transistor ; a light emitting region having a common power supply line for supplying current to the light - emitting layer portion ; and a peripheral common power supply line having at least one curved portion and connected to the common power supply line on a panel of a non - light emitting region except the light emitting region , wherein the common power supply line has a reduced wiring width while maintaining a constant wiring resistance to thereby reduce the total size of the display panel .