An image reading apparatus is disclosed that includes a contact glass on which a document is placed; an imaging device configured to image a document image based on light reflected from the document through the contact glass; plural line image sensors arranged along a main scanning direction at positions where the document image is imaged and configured so that end portions of the line image sensors adjacent to each other similarly read same image data imaged at an overlapping area; a transmitted light quantity reduction unit disposed in the overlapping area on the contact glass and configured to reduce transmitted light quantity of a light transmitted through the contact glass; and a signal correction device configured to correct the signal intensity of the image data similarly read by the line image sensors adjacent to each other.