An auto document feeder includes a lead path, a first reverse path, a second reverse path, and a both surfaces eject path. The lead path guides a document from a left side to a right side of a read position. The first and second reverse paths are connected to the lead path, and reverse the document to guide the document from the right side to the left side of the read position. A both surfaces eject path is connected to the first and second reverse paths and guides the document whose image information of a second surface has been read to eject further to the right side than the read position. A shared curve path shared by the lead path and the both surfaces eject path includes a portion between the read position and a portion in which a lead curve path protrudes the most.