A liquid crystal display device includes a liquid crystal display panel; a backlight assembly providing light to the liquid crystal display panel and including an optical sheet; a bottom cover supporting the liquid crystal display panel and the backlight assembly and including a side surface having an indented portion; and a fixing unit combined with the indented portion of the side surface of the bottom cover to fix the optical sheet, wherein the optical sheet includes a projecting portion, which is cut to include a fixing part and bridges and is united with the fixing unit.