A document feeder of the invention is formed of a platen for reading and scanning original documents, a document tray for placing the original documents to be processed situated above the platen, and an ejection tray for receiving the original documents after being processed situated between the platen and the document tray spaced apart from each other in a vertical direction. A transfer path is formed for transferring the original documents from the document tray to the ejection tray through a reading position on the platen. An exit of the document tray, an entrance of the ejection tray and the reading position on the platen are arranged laterally in this order above the platen with a predetermined distance spaced apart from each other. A separating portion for separating the original documents one by one is situated between the exit of the document tray and the entrance of the ejection tray to be laterally spaced apart from each other. The document feeder is made compact in size.