A data driver drives comb-tooth distributed data lines of an electro-optical device in units of a predetermined number of data lines. The data driver includes first and second divided gray-scale buses, a gray-scale bus to which gray-scale data is supplied corresponding to an arrangement order of each of the data lines, a gray-scale data distribution circuit which distributes and outputs the gray-scale data supplied to the gray-scale bus to the first and second divided gray-scale buses, a first driver circuit which drives the data lines belonging to a first group among the data lines based on the gray-scale data output to the first divided gray-scale bus by the gray-scale data distribution circuit, and a second driver circuit which drives the data lines belonging to a second group among the data lines based on the gray-scale data output to the second divided gray-scale bus by the gray-scale data distribution circuit.