An organic light-emitting display device includes: a display panel comprising a plurality of pixels, wherein each of the plurality of pixels comprises an organic light-emitting diode (OLED) configured to emit light of one color from among a plurality of colors comprising red, green, and blue; a degradation determiner configured to determine a degree of degradation of the OLED from a value of accumulated image data that is input to each of the plurality of pixels; a current sensor configured to apply a sensing voltage to the OLED and to measure a current corresponding to the sensing voltage; and a degradation calculator configured to calculate an amount of degradation of the OLED from the current measured by the current sensor.