A recycle document feeder according to the present invention includes a pair of document width regulating guides (9a, 9b) for guiding opposite edges of document originals (D) fed back onto a document placing plate (8) for alignment thereof with respect to the width thereof. With this construction, if the document width regulating guides (9a, 9b) each had a small length (A) as measured along a document transportation direction, the document originals (D) fed back onto the document placing plate (8) could not properly be aligned by the document width regulating guides (9a, 9b) thereby to be randomly stacked on the skew with respect to the document transportation direction. In view of this, the document width regulating guides (9a, 9b) are constructed so as to guide the document originals fed back onto the document placing plate (8) from a document discharge portion (30) over a distance equivalent to or greater than 60% of the length of a smallest document original (as measured along the transportation direction) which is to be possibly transported by the recycle document feeder.