A sheet feeder comprising: sheet stacking means for stacking sheets (D); sheet pickup means for picking up a sheet (D) from one side of the stacked sheets (D) on the sheet stacking means ; and sheet separating and feeding means , formed downstream of the sheet pickup means in a sheet feeding direction (s), for separately feeding sheets (D) one by one to a conveyance path , wherein a sheet (D) picked up from the sheet stacking means by the sheet pickup means is separately fed from the sheet stacking means to the conveyance path on the downstream side in the sheet feeding direction (s) via an inclined surface inclining in the sheet feeding direction (s), orientation holding means for holding a feed orientation of a sheet (D) currently being separately fed by acting on the sheet (D) is formed between the sheet pickup means and the sheet separating and feeding means , the orientation holding means is displaceable between a position where the orientation holding means projects from the inclined surface and a position where the orientation holding means is retracted, in the vicinity of an intersection between the sheet stacking means and the inclined surface , and a projection amount of the orientation holding means from the inclined surface substantially increases as the number of stacked sheets (D) decreases, and the orientation holding means has a function of holding the feed orientation of a sheet (D) picked up from the sheet stacking means by the sheet pickup means , by pushing up the sheet (D) in the projecting position, characterized in that the orientation holding means is accommodated in a recess of the inclined surface at the retracted position. sheet stacking means for stacking sheets (D); sheet pickup means for picking up a sheet (D) from one side of the stacked sheets (D) on the sheet stacking means ; and sheet separating and feeding means , formed downstream of the sheet pickup means in a sheet feeding direction (s), for separately feeding sheets (D) one by one to a conveyance path , wherein a sheet (D) picked up from the sheet stacking means by the sheet pickup means is separately fed from the sheet stacking means to the conveyance path on the downstream side in the sheet feeding direction (s) via an inclined surface inclining in the sheet feeding direction (s), orientation holding means for holding a feed orientation of a sheet (D) currently being separately fed by acting on the sheet (D) is formed between the sheet pickup means and the sheet separating and feeding means , the orientation holding means is displaceable between a position where the orientation holding means projects from the inclined surface and a position where the orientation holding means is retracted, in the vicinity of an intersection between the sheet stacking means and the inclined surface , and a projection amount of the orientation holding means from the inclined surface substantially increases as the number of stacked sheets (D) decreases, and the orientation holding means has a function of holding the feed orientation of a sheet (D) picked up from the sheet stacking means by the sheet pickup means , by pushing up the sheet (D) in the projecting position, <EOS>