An image reading device includes: a document table on which a document G is placed; a line light source configured to illuminate the document G; an erecting equal-magnification lens array plate configured to receive light reflected from the document G and form an erect equal-magnification image on a predetermined image plane; and a line image sensor configured to receive the erect equal-magnification image formed by the erecting equal-magnification lens array plate. The erecting equal-magnification lens array plate includes: first and second lens array plates formed with a plurality of lenses on both sides thereof; a first shielding member provided on the first outer side surface of the first lens array plate; and a light-shielding wall provided upright on the top surface of the first light-shielding member and configured to shield light reflected by the document table.