A display device includes a plurality of pixels, each pixel including an organic light emitting diode (OLED) and a driving transistor, a sustain power supply unit applying a first sustain voltage to a plurality of data lines connected to the plurality of pixels, and a data driver applying one of a data signal and a second sustain voltage to the plurality of data lines. For each pixel, the sustain power supply unit applies the first sustain voltage as a first level voltage to reset a gate voltage of the driving transistor and applies the first sustain voltage as a second level voltage to increase the gate voltage of the driving transistor. When an anode voltage of the OLED in each pixel is discharged to be reset, the anode voltage of the OLED is controlled according to a voltage difference between the first level voltage and the second level voltage.