Disclosed is an organic light emitting display device and a method of driving the same that can improve compensation performance of degradation of a driving TFT. A method of driving an organic light emitting display device comprises generating an estimated degradation value of a driving TFT by using accumulated data through input data counting; compensating all the pixels of a display panel by using a first gain value, which is initially set, and the estimated degradation value; generating a sensing value by sensing all or some of the pixels of the display panel after driving is performed for a certain time; generating a second gain value by compensating the first gain value if an error between the estimated degradation value and the sensing value is more than a reference value; generating compensation data by compensating the estimated degradation value by using the second gain value; and compensating all the pixels of the display panel by using the compensation data.