An organic light emitting display is capable of preventing brightness from being non-uniform due to IR drop so as to improve reliability of the organic light emitting display. The organic light emitting display comprises: a display panel having a display region and a non-display region; a plurality of sub pixels defined by perpendicularly intersecting a plurality of gate lines and a plurality of data lines formed in the display region of the display panel; and a power source supply pad unit provided in the non-display region of the display panel for supplying a power source voltage to the plurality of sub pixels. A resistance value of sub pixels arranged in a first region adjacent to the power source supply pad unit is higher than a resistance value of sub pixels of a second region which is separated from the power source supply pad unit, with the first region interposed therebetween.