Disclosed is a display device, which includes a display panel, a controller that receives an image signal and an external synchronization signal and generates a control signal, and a driver that generates a driving signal in response the control signal and provides the driving signal to the display panel. The controller includes a synchronization signal generator that generates an internal synchronization signal based on a reference clock signal, a corrector that corrects the internal synchronization signal to generate a corrected synchronization signal, and a control signal generator that generates the control signal, and the control signal generator generates the control signal based on the external synchronization signal when the external synchronization signal is in a normal state, and generates the control signal based on the internal synchronization signal when the external synchronization signal is in an abnormal state.