A foldable display device includes a display panel, a back plate disposed under the display panel, and a support structure disposed under the back plate and having a bendable area and non-bendable areas disposed on sides of the bendable area. The support structure includes a first support plate having a plurality of opening patterns disposed in the bendable area, and a second support plate disposed on the first support plate and made of a different material from a material of the first support plate. One of the back plate and the second support plate includes a polymer film having a maximum reflectance within a wavelength range of approximately 400 nm to 500 nm. The other one of the back plate and the second support plate includes a polymer film having a maximum light absorbance within a wavelength range of approximately 400 nm to 500 nm.