Abstract: A foldable display device includes a first support plate and a second support plate, a display panel disposed on the first support plate and the second support plate and a hinge assembly disposed between the first support plate and the second support plate, wherein the hinge assembly includes, a first hinge arm and a second hinge arm rotatably connected to each other, a first virtual axis gear coupled to the first hinge arm, a second virtual axis gear coupled to the second hinge arm, a first rotational gear and a second rotational gear disposed to mesh with each other between the first virtual axis gear and the second virtual axis gear and a first gear arm and a second gear arm fastened to interlock with the first virtual axis gear and the second virtual axis gear, wherein the first support plate, the second support plate, and the display panel perform folding and unfolding operations about a rotation axis different from central axes of the first virtual axis gear and the second virtual axis gear.