A driving apparatus for a display device includes a plurality of pixels arranged in a matrix, and each pixel includes first and second sub-pixels. The driving apparatus includes a memory for storing digital data, a controller for calling the digital data to output the digital data together with a clock signal and at least one selection signal, and a gray voltage generator formed of an integrated circuit to receive the digital data from the controller and to generate gray reference voltage sets. The gray voltage generator includes first and second registers for storing the digital data, a selector including a plurality of multiplexers for receiving the outputs of the first and second registers, and a converter including a plurality of digital-analog converters connected to the multiplexers. As described above, the gray voltage generator is provided in the form of a chip so that it is possible to reduce the area occupied on a printed circuit board (PCB) and to reduce the cost of the gray voltage generator.