An image reading device includes a light source part in which plural point light sources are arrayed in parallel to a main scanning direction, a line sensor part in which plural light quantity sensors are arrayed in parallel to the main scanning direction, a reduction optical system containing a lens and focusing a reflected light beam indicating image information of a document irradiated by a light beam from the light source part, on the line sensor part to read the image information, and a control part configured to control a quantity of irradiating light of each point light source of the light source part in accordance with an optical characteristic of the lens of the reduction optical system.