Image reading apparatus and image forming apparatus

An image reading apparatus configured to read an image of an original, the image reading apparatus comprising:

• a light source configured to irradiate the original with light;
• an optical system configured to condense and image a light beam emitted from the light source and reflected from a surface of the original;
• a substrate member having a photoelectric conversion unit arranged in an imaging position of the optical system;
• 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 that protrudes toward the other of the support member and the fixing member,
• wherein the other of the support member and the fixing member has a recessed portion that is opposed to the protruding portion,
• wherein the protruding portion is arranged to protrude in the recessed portion in a non-contact state to maintain a gap between the protruding portion and the recessed portion, and
• wherein the adhesive is applied to the gap between the protruding portion and the recessed portion.