The present invention provides an OLED display device including a display panel, a data driver and a timing controller. The display panel has sub-pixels for displaying images. The data driver supplies a data signal to data lines of the sub-pixels. The timing controller supplies the data signal to the data driver and controls the data driver. The data driver outputs a stress prevention voltage for preventing application of stress to driving transistors included in the sub-pixels in response to a stress compensation signal output from the timing controller, and the stress prevention voltage is applied to M (M being an integer equal to or greater than 1) sub-pixels selected per frame.