A foldable display device includes a foldable display panel and a foldable cover window disposed on the foldable display panel. The foldable cover window includes a flexible film and a first hard coating layer located on the flexible film with the first hard coating layer including a base material in combination with a linker material. The base material is a siloxane-based resin and the linker material is one of: a urethane-acrylic-based linker, an acrylic-based linker, and an epoxy-based linker.