A liquid crystal display device, comprising: a liquid crystal panel; and a backlight unit configured to irradiate light onto the liquid crystal panel; the backlight unit comprises: a light source; a light guide plate below the liquid crystal panel and comprising a light emitting surface through which incident light supplied from the light source is emitted toward the liquid crystal panel; and a plurality of protrusion patterns extending outward from a surface of the light guide plate opposite to the light emitting surface, wherein the protrusion patterns are arranged in a matrix form and spaced apart from each others at intervals, a prism sheet located between the light guide plate and the liquid crystal panel; and each of the plurality of protrusion patterns comprising a first triangular prism extending in a first direction and a second triangular prism extending in a second direction crossing the first direction such that the first triangular prism and the second triangular prism cross through each other, the first triangular prism being longer along the first direction than the second triangular prism being along the second direction, characterized in that each of the plurality of protrusion patterns comprises a third triangular prism oriented parallel to the second triangular prism and the second direction, the third triangular prism being laterally offset from the second triangular prism along the first direction, the third triangular prism intersecting with the first triangular prism at a side of the first triangular prism opposed to the side of the first triangular prism at which the second triangular prism is located. a liquid crystal panel; and a backlight unit configured to irradiate light onto the liquid crystal panel; the backlight unit comprises: a light source; a light guide plate below the liquid crystal panel and comprising a light emitting surface through which incident light supplied from the light source is emitted toward the liquid crystal panel; and a plurality of protrusion patterns extending outward from a surface of the light guide plate opposite to the light emitting surface, wherein the protrusion patterns are arranged in a matrix form and spaced apart from each others at intervals, a prism sheet located between the light guide plate and the liquid crystal panel; and each of the plurality of protrusion patterns comprising a first triangular prism extending in a first direction and a second triangular prism extending in a second direction crossing the first direction such that the first triangular prism and the second triangular prism cross through each other, the first triangular prism being longer along the first direction than the second triangular prism being along the second direction, characterized in that each of the plurality of protrusion patterns comprises a third triangular prism oriented parallel to the second triangular prism and the second direction, the third triangular prism being laterally offset from the second triangular prism along the first direction, the third triangular prism intersecting with the first triangular prism at a side of the first triangular prism opposed to the side of the first triangular prism at which the second triangular prism is located. a light source; a light guide plate below the liquid crystal panel and comprising a light emitting surface through which incident light supplied from the light source is emitted toward the liquid crystal panel; and a plurality of protrusion patterns extending outward from a surface of the light guide plate opposite to the light emitting surface, wherein the protrusion patterns are arranged in a matrix form and spaced apart from each others at intervals, a prism sheet located between the light guide plate and the liquid crystal panel; and each of the plurality of protrusion patterns comprising a first triangular prism extending in a first direction and a second triangular prism extending in a second direction crossing the first direction such that the first triangular prism and the second triangular prism cross through each other, the first triangular prism being longer along the first direction than the second triangular prism being along the second direction, characterized in that each of the plurality of protrusion patterns comprises a third triangular prism oriented parallel to the second triangular prism and the second direction, the third triangular prism being laterally offset from the second triangular prism along the first direction, the third triangular prism intersecting with the first triangular prism at a side of the first triangular prism opposed to the side of the first triangular prism at which the second triangular prism is located.