The general inventive concepts provide a side-light type backlight unit. The side-light type backlight unit comprises a light guide plate and a light source located at the side of the light incident surface of the light guide plate. The light source comprises a circuit board which comprises a first region opposite to the light incident surface of the light guide plate and a second region adjacent to the first region. The first region and the second region are provided with LED lamps. By arranging LED lamps in both the first region and the second region of the circuit board of the side-light type backlight unit, the incident light of the side-light type backlight unit is increased, thereby improving the luminance of the side-light type backlight unit in 3D state. The disclosure further provides a display device comprising such a side-light type backlight unit.