A digital-to-analog converter (DAC) for a display device is provided. The DAC includes an amplifier and a current decoder. The amplifier receives a gradation voltage with respect to upper bits in data of k bits through a non-inverting input terminal, and varies the input gradation voltage according to a voltage applied to an inverting input terminal. The current decoder allows a predetermined constant current to flow therethrough according to input data of lower bits, which do not include the upper bits, to thereby vary the voltage applied to the inverting input terminal. The current decoder further adjusts the gradation voltage outputted by the amplifier according to the varied voltage.