The organic light emitting display device according to the present disclosure comprises an input unit configured to receive image data input at a variable frame frequency, a sensing control unit configured to generate a sensing control signal for sensing pixels to which the image data is to be applied, in a vertical blank period varying according to the variable frame frequency and a TFT compensating unit configured to sense driving characteristics of a driving element included in the pixels according to the sensing control signal to output a first sensing result. Among one variable frame period, a vertical active period for applying the image data to the pixels is fixed and the vertical blank period in which no image data is applied to the pixels is varied according to the variable frame frequency.