PURPOSE: To reliably feed a sheet in an automatic sheet feeder of a facsimile or the like by detecting a failure in feeding a document independent of inclination of a document table and applying advancing force to the document by means of an auxiliary sheet feed roller.

CONSTITUTION: An auxiliary sheet feed roller 7 always kept apart from the upper surface of a document 2 is disposed on this side of a sheet feed roller 3. When detectors 21, 22, 24 disposed on a document path 23 detects that the leading end of a document 2 to be fed out is not positioned at a designated place at the time of feeding, the auxiliary sheet feed roller 7 is brought into pressure contact with the upper surface of the document 2 until the leading end of the document 2 reaches the detecting position. At this time, driving force is applied to a separation roller 4, so that the uppermost document 2 is fed out to the document path 23 by action of the rollers 3, 4. Although the detector 24 detects the trailing end of the document, if the subsequent document is not detected by the detector 22, a solenoid 12 is energized so that the advancing force is applied to the subsequent document 2 by the roller 7.