A driving controller includes an overcurrent load calculator calculating a load of an input image signal, comparing the load and a reference load, and outputting a first signal corresponding to a first comparison result, an overcurrent reference controller analyzing a grayscale of the input image signal and outputting one of a first reference current signal corresponding to the grayscale and a second reference current signal, whose current level is higher than that of the first reference current signal, as a reference current signal, a current sensor receiving a feedback current signal, comparing a current level of the feedback current signal and a current level of the reference current signal, and outputting a second signal corresponding to a second comparison result, and a voltage controller outputting a voltage control signal for adjusting a voltage level of a driving voltage, based on the first signal and the second signal.