Provided is a document reading apparatus in which an original document fed by feeding means to contact glass having a predetermined reading position is read by reading means. Then, the document reading apparatus is provided with a guide unit having a guide member for guiding the original document to be fed to the contact glass, and a backup unit to back up the original document to be read, and the guide unit is configured to be able to travel between a close position to near the contact glass and an open position to distance from the contact glass. In the guide unit is formed a concave portion for removably accommodating the backup unit, and the backup unit is configured so that an original document guide face of the guide member and an original document guide face in the backup unit form a continuous guide face when the guide unit travels to the close position.Then, the guide unit is moved to the open position to perform cleaning of the backup unit and contact glass. Further, the backup unit is removed to perform maintenance.