A liquid crystal display device includes: a liquid crystal display panel; a light guide plate having adjacent first and second light incidence surfaces below the liquid crystal display panel; a reflection plate disposed under the light guide plate; and first and second light-emitting diodes (LEDs) facing the first and second light incidence surfaces, respectively, wherein the light guide plate comprises: a first prism pattern configured on a lower surface of the light guide plate and extending in a first direction parallel to the first light incidence surface; and a second prism pattern configured on an upper surface of the light guide plate and extending in a second direction parallel to the second light incidence surface.