An image reading device including: plural point light sources, each point light source being disposed at a placement interval F in a first direction; a light guiding body having an exit surface, incident light from the plural light sources exiting from the exit surface to a surface to be read, and a width S of the exit surface, in a second direction intersecting with the first direction, being smaller than the placement interval F; a light diffusing portion which diffuses light exiting from the exit surface, at an angle that is greater in the first direction than in the second direction; and a reading portion which receives light reflected at the surface to be read, and reads an image at the surface to be read, is provided.