Embodiments of the present disclosure are related to a backlight unit and a display device, and the backlight unit in which an optical plate including an engraved pattern in which a color conversion material is disposed is positioned on a light source can be provided. As the color conversion material is disposed in the engraved pattern, a change of the color conversion material by an external factor can be prevented and an amount of the color conversion material can be reduced, thus the backlight unit providing an image quality greater or equal to a certain level and with improved reliability can be implemented easily.