An illumination device (30) includes a plurality of light source units (BLU) each having a light guide plate (1) and a plurality of light sources (21). The light guide plate (1) has an illumination region (4) through which incident beams of light from the light sources (21) are emitted outward and a light guide region (3) through which the incident beams of light from the light sources (21) are guided toward the illumination region (4), with the light guide region (3) and the illumination region (4) laid side-by-side. The illumination region (4) is divided into a plurality of light-emitting sections by slit sections (8), provided in such a way as to extend along directions of optical axes of the light sources (21), which restrict transmission of light. At least one of the light sources (21) is provided to each of the light-emitting sections in such a way as to be placed side-by-side along the light guide region (3). Light source units (20) adjacent to each other along the directions of the optical axes of the light sources (21) are disposed so that the illumination region (4) of one of the light source units (BLU) covers at least a part of the light guide region (3) of the other light source unit (BLU). This makes it possible to retain the strength of the illumination device as a combination of light guide blocks while reducing leakage of light into an adjacent area.