A document setting position on a document set tray 101 where a small-sized document is set is determined by positionally matching a near-side reference position (a position of or set in the vicinity of a user-side end of a document placement surface of the document set tray 101) and a user-side edge of the document. An output tray 114 has a window 115 made from a transparent material so as to allow a user to see a document setting position on the document set tray 101 where the user sets a small-sized document. This makes it possible to adjust a position on the document set tray 101 where a document is placed, in use of an image reading apparatus 100 in which the document set tray 101 for placing thereon a document to be read is provided below the output tray 114 for placing a read document thereon.