A driving controller of a display device, the controller including a segment divider configured to divide the image signal into a plurality of segments and define a predetermined number of adjacent segments among the plurality of segments as a segment block, an image signal adder configured to add up a gray scale value of the image signal of each of the predetermined number of adjacent segments and output the added-up gray scale values, an average gray scale calculator configured to receive the added-up gray scale values and output an average gray scale value, a correction circuit configured to output corrected added-up gray scale values obtained by adding a weight value to each of the added-up gray scale values on the basis of the average gray scale value, and a driving frequency determiner configured to determine the driving frequency of the display device on the basis of the corrected added-up gray scale values.