The present invention is an organic light-emitting diode, and a drive transistor for driving the OLED, data lines and a plurality of pixels coupled to the sensing lines are formed, the source of the driving transistor according to the data voltage applied to the pixels - It relates to the drain current to the sensing method of the OLED display to obtain a sensed current value. The organic light emitting display device sensing method of the present invention is to apply a step and black gray-scale data voltage to the reference pixels that define the pixel group including from a plurality of pixels arranged in a horizontal line, the reference-pixel and more than one effective pixel , obtaining a black gradation current sensing value, the effective pixel by applying a predetermined gray-scale data voltage having a higher gray level than the black gray level in a given gray level comprising: obtaining a current sensing value and the black gradation current sensing value from the predetermined gradation current sensing value subtracts the, including the step of obtaining a common noise is canceled pixel current sensing value.