A backlight assembly includes a light source unit configured to supply light, a light guide plate configured to guide light incident from the light source unit to an upper surface thereof, a reverse prism sheet disposed on the light guide plate and having a prism-shaped lower surface and an auxiliary film disposed between the light guide plate and the reverse prism sheet, in which the light guide plate includes a light-incident portion on which light is incident from the light source unit and a light-facing portion facing the light-incident portion.