According to one embodiment, an auto document feeding device comprises: a document placing section on which documents are placed; a first gate configured to divert the documents in a first direction or a second direction; a first conveying unit or a second conveying unit configured to lead the documents to the image scanning unit; a paper discharging and conveying unit configured to lead the documents from the image scanning unit in the direction of the paper discharge tray; a reversing roller configured to switch back the documents passed through the paper discharging and conveying unit; a reversing and conveying unit configured to convey the documents from the reversing roller to the first gate; and a second gate configured to divert the documents passed through the paper discharging and conveying unit to the reversing and conveying unit.