There is provided a high-efficiency and high-definition liquid crystal display device in which a white light source is constituted by using a fluorescent substance composed of a quantum dot having a minute particle size, and an LED light-emitting element, light from the light source is allowed to be incident from one lateral surface of a backlight provided on a rear surface of the liquid crystal display device, and thus an amount of the quantum dot fluorescent substance that is used is reduced, and the thickness of the liquid crystal display device is made smaller as a whole.