A backlight unit and a display device including the backlight unit are discussed. According to an embodiment, a light generating device comprising: a first layer; light source devices disposed on the first layer and configured to emit light; a reflection layer disposed on the first layer and configured to reflect the light emitted from the light source devices; a second layer covering the light source devices and the reflection layer; a diffusion layer disposed on the second layer and configured to diffuse the light emitted from the light source devices; and an auxiliary layer having light shielding members placed between the second layer and the diffusion layer, the auxiliary layer being separated from the second layer so as to create an air space between a surface of the second layer and surfaces of the light shielding members, the air space extending along the light source devices.