Described is a liquid crystal display device including an edge light source array or a direct-type light source array and a group of optical sheets disposed over a light guide plate. The liquid crystal display device has at least one foot that extends towards the side of the bottom cover from one edge of a top sheet among the group of optical sheets. The at least one foot partially fixes the group of optical sheets to prevent movement in the vertical and horizontal directions in an upright display orientation, while allowing for expansion of the optical sheets during manufacturing.