A display device having a display panel including a plurality of data lines; a data driver including at least one data driving circuit chip which transmits data signals to the plurality of data lines; and a signal controller transmitting a dummy control signal and an output image signal to a first data driving circuit chip of at least one data driving circuit chip. The first data driving circuit chip may include zero or more dummy channels which are not connected with the data lines, and the dummy control signal includes information on positions of the dummy channels included in the first data driving circuit chip and information regarding the number of dummy channels.