An organic light emitting display device includes: a pixel unit including a plurality of pixels; a scan driver for sequentially supplying a scan signal to the pixels through scan lines, wherein the scan signal includes k (k is a natural number) bias pulses for applying a bias voltage and one write pulse for applying a data voltage; a data corrector for correcting a first grayscale value that is a grayscale value of a (j, i) pixel (i and j are natural numbers) among the pixels, based on a difference between the first grayscale value and a second grayscale value that is a grayscale value of a (j+2k, i) pixel among the pixels; and a data driver for supplying a data voltage corresponding to each of the grayscale values to the pixel unit through a plurality of data lines.