An image reading apparatus includes a scanner unit including a first image reading portion configured to read an image of a first surface of a document through a first flow-reading glass, an ADF including a second image reading portion disposed on an opposite side of the first image reading portion across a sheet conveyance path and reading an image of a second surface of the document through a second flow-reading glass. The image reading apparatus further includes a gap forming member disposed on either one of the second flow-reading glass and a moving guide unit and abutting with another one of them. The moving guide unit is provided in the scanner unit and is urged by springs to be movable toward the second flow-reading glass.