An organic light emitting display (OLED) device capable of compensating for threshold voltage of a driving transistor in which this OLED device uses a scan driver to sequentially supply scan signals to scan lines. A data driver supplies data signals to data lines when the scan signals are supplied with pixels positioned at the intersections of the scan lines and the data lines. A common circuit unit formed in every horizontal line, receiving one or more external power sources required in driving the pixels and transferring the received external power to pixels positioned in the same horizontal lines.