A foldable display device includes a display panel. The display panel includes a plurality of display areas divided by at least one or more folding lines. A plurality of data integrated circuits is configured to output a data voltage to the plurality of display areas. Each of the plurality of data integrated circuits includes at least one or more gamma voltage generators that are configured to output a plurality of gamma voltages. The at least one or more gamma voltage generators are connected by an external gamma line, so that boundaries between the display areas may be minimized or reduced.