An organic light emitting display device includes a display panel including a pixel at an intersection of a data line, a feedback line, and a scan line; a data driver configured to provide a data signal to the pixel through the data line; and a sensing unit configured to generate a reference voltage based on the data signal, to generate first sensing data based on a sensing current that flows through the feedback line in response to the reference voltage, and to generate second sensing data by digital-converting the reference voltage.