Abstract: An automatic document feeder for facsimiles for reliably feeding at least 30 sheets of documents into a facsimile one by one without misfeeding is disclosed. The document feeder comprises an ADF (automatic document feeding) roller for feeding documents. A rotating shaft is coupled to the ADF roller such that it is run idle. At least one cam roller is mounted on the rotating shaft for feeding a misfed document. A drive motor for generation of document feeding force is coupled to a drive gear so as to rotate this drive gear. A power transmission unit transmits the rotational force of the drive gear to both the ADF roller and the cam roller so as to rotate these rollers. The power transmitting unit comprises a driven gear gearing into the drive gear and mounted on the rotating shaft such that it is run idle. A driven gear flange is formed on a side of the driven gear. A bush is fixed to the rotating shaft.