An illumination device includes a plurality of light sources arranged in a row, a light guide plate having a plate shape and including a first end face at an outer peripheral end face of the light guide plate and a first main surface included in a pair of main surfaces of the light guide plate, the first end face facing the plurality of light sources and being configured to receive incident light, the first main surface being configured to emit light, and a plurality of first lenses disposed at the first main surface, arranged along a first direction, and extending along a second direction, the first direction being an arrangement direction of the plurality of light sources, the second direction intersecting the first direction and extending along the first main surface.