A method of driving an organic light emitting display device includes generating a luminance map for a plurality of pixels by applying the same driving voltage to driving transistors formed in the plurality of pixels of a panel and by capturing luminances of the pixels, generating a threshold voltage map by calculating threshold voltage correction values that compensate for threshold voltages of the driving transistors associated with the luminances of the pixels. A lookup table is generated by sampling the threshold voltage correction values stored in the threshold voltage map. Threshold voltage correction values are restored by interpolating the sampled threshold voltage correction values, and correcting a driving voltage by adding the restored threshold voltage correction values to input gray level data and by providing the added value to the panel.