An infinitely expandable display device according to an embodiment of the present disclosure includes a plurality of display units including a plurality of data drivers connected through a bidirectional interface circuit, and a timing controller commonly connected to the display units through the bidirectional interface circuit. Each of the data drivers includes a first reception circuit configured to receive a first interface signal in a first direction, a first transmission circuit configured to transmit the first interface signal in the first direction, a second reception circuit configured to receive a second interface signal in a second direction opposite the first direction, a second transmission circuit configured to transmit the second interface signal in the second direction, and a switch circuit SWP connected to the first transmission circuit, the second transmission circuit, and the second reception circuit.