A lower-power driving display device and a driving method. The driving method of the display device includes dividing the plurality of output buffers of the data driver into a plurality of output buffer groups, each of the plurality of output buffers being configured to apply the data voltage to each of the plurality of data lines connected with the display panel, and determining the magnitude of a bias current supplied to an output buffer on the basis of a pattern of a data voltage output by the output buffer which belongs to each of the plurality of divided output buffer groups.