A data driver includes a data driving chip, a first data transmitting line, a second data transmitting line, a first shielding line and a second shielding line. The first data transmitting line and the second data transmitting line are configured to transmit a data signal to the data driving chip. The first shielding line is disposed at a first side with respect to the first data transmitting line. A ground voltage is applied to the first shielding line. The second shielding line is disposed at a second side with respect to the second transmitting line. The second side is opposite to the first side. The ground voltage is applied to the second shielding line.