A display device includes a light source to emit light, a light guide plate on which the light emitted from the light source is incident and which irradiates light through a first and a second surface of the light guide plate, a quantum dot sheet on which the light irradiated through the first surface of the light guide plate is incident and which irradiates blue light, green light and red light, a reflective sheet for reflecting the irradiated light to the light guide plate, and a light-converting material at an edge portion of the light guide plate, the quantum dot sheet and the reflective sheet, for converting the light into a yellow light, green light or red light. The light incident on the quantum dot sheet includes the light emitted from the light source and the yellow light, the green light or the red light.