An image reading apparatus configured to read an image of an original, including: a light source configured to irradiate the original with light; an optical system configured to condense and image a light beam from the light source reflected from the original; a substrate member having a photoelectric conversion unit; a fixing member fixed to the substrate member; a support member configured to support the optical system; and an adhesive bonding the fixing member and the support member together, wherein one of the support member and the fixing member has a protruding portion which protrudes toward the other of the support member and the fixing member, the other has a recessed portion opposed to the protruding portion, the protruding portion protrudes in the recessed portion in a non-contact state to maintain a gap between the protruding portion and the recessed portion, and the adhesive is applied to the gap.