A display device includes a display panel which displays an image, a backlight unit which supplies the display panel with light, an upper cover, and a lower cover. The upper and lower covers accommodate the display panel and the backlight unit. The backlight unit includes light guide plates spaced apart from each other, a light source part, an optical member and an optical diffusion member overlapping a space between the light guide plates. The optical diffusion member includes a diffusing part and a supporting part. The diffusing part faces the optical member, overlaps the space between the light guide plates, and diffuses light emitted from the light source part toward the optical member through the space between the light guide plates. The supporting part protrudes from a surface of the diffusing part which is opposite to the optical member, and is in a space between the light sources.