A data driver is provided comprising: a gamma correction resistor for outputting a gray scale voltage, a gray scale voltage supply switch, first and second operational amplifiers for driving a first and second data lines, inputs of these first and second operational amplifiers being electrically coupled with the gray scale voltage signal line, and first and second bypass switches for bypassing each operational amplifier. In a first period of a drive period, the first and second data lines are driven by the first and second operational amplifiers based on the gray scale voltage of a gray scale voltage signal. In a second period of the drive period, the gray scale voltage supply switch is set to a cut-off state, whereby the first data line is electrically coupled with the second data line via the gray scale voltage signal line, the first bypass switch, and the second bypass switch.