A light irradiation device includes a light source having a plurality of solid-state elements disposed on a substrate to be defined by a first direction and a second direction in a plurality of rows and irradiate the irradiation target with light from a third direction, an optical element refracting light from the solid-state elements, emitting the light and narrowing a spread angle of light to be emitted from the solid-state elements relative to the third direction, a first reflection portion having at least two first reflection surfaces on a downstream side in the third direction of the irradiation target and reflecting a part of light incident on the first reflection surface to the irradiation target, and a second reflection portion having a pair of second reflection surfaces disposed between the optical element and the first reflection portion and guiding light from the optical element to the first reflection surface.
