A method of digital-driving an organic light emitting display device, which divides one frame into a plurality of sub-frames, is provided. In this method, a total number of scan operations, which are to be performed during the frame, is calculated based on a number of scan-lines and a number of the sub-frames, an emission time of each of the sub-frames is set based on a gray level maximum value and the total number of the scan operations, the emission times of the sub-frames are modified by permitting errors to the emission times of the sub-frames to control a sum of the emission times of the sub-frames to be equal to the total number of the scan operations, and each sub-frame scan timing of the scan-lines is sequentially shifted by N horizontal scan intervals, where N is the number of the sub-frames.