An automatic document feeder (ADF), which is capable of feeding a document for double-sided reading, includes an input tray, an output tray, which are vertically arranged, a U-shaped document feed path, which is made up of an upper portion, a curved portion, and a lower portion, feeding rollers disposed in the document feed path, a bidirectional feed path connected to a connection position, a bidirectional feed roller provided in the bidirectional feed path, a bypass connecting a branch position and the connection position, and an ADF cover, which is rotatable with respect to an ADF frame. A paper jam is readily cleared with a simple structure and reasonable cost.