A foldable display device includes a display panel including first and second display areas and a folding part between the first and second display areas; first and second system units disposed under the display panel and corresponding to the first and second display areas, respectively, an elastic plate between the display panel and the first and second system units; and a hinge system corresponding to the folding part and disposed on rear surfaces of the first and second system units, the hinge system including a first hinge portion on the rear surface of the first system unit and a second hinge portion on the rear surface of the second system unit, wherein the first and second hinge portions are rotatably hinge-combined with each other.