A driving controller includes an oscillator and a signal generator. The oscillator is configured to generate an oscillation signal based on an input current. The signal generator is configured to generate a gate driving signal and a data driving signal based on the oscillation signal. The oscillator is configured to maintain a frequency of one horizontal period of the oscillation signal to be constant when an oscillation fundamental frequency is shifted. When the oscillation fundamental frequency is f0 and a fundamental constant is N0, the frequency of one horizontal period is f0/N0.