An organic light-emitting display apparatus including a display including pixels arranged in an array, a sensor for detecting respective current characteristics of the pixels, a current sensor for receiving a first current from a first pixel of the pixels, for outputting a first voltage corresponding to the first current, for receiving a second current from a second pixel of the pixels, and for outputting a second voltage corresponding to the second current, a level shifter for receiving the first and second voltages and for generating first and second shift voltages respectively corresponding to the first and second voltages, an intermediate voltage of the first and second voltages being equal to a conversion reference voltage, and an analog-to-digital converter for receiving the first and second shift voltages and for outputting a digital value corresponding to a difference between the first and second shift voltages based on the conversion reference voltage.