A driving device of a display device includes: a reference voltage generator configured to receive a high potential power supply voltage, a low potential power supply voltage and a medium power supply voltage and to generate reference voltages between the high potential power supply voltage and the low potential power supply voltage, where the low potential power supply voltage is lower than the high potential power supply voltage, and the medium power supply voltage has a value between the high potential power supply voltage and the low potential power supply voltage; a gray reference voltage generator configured to receive and divide the reference voltages and to generate gray reference voltages; and a data driver configured to receive the gray reference voltages and the high and medium potential power supply voltages, and to generate data voltages using the gray reference voltages and the high and medium potential power supply voltages.