To provide a document feeder capable of reversely discharging a preceding read-out document during reading out a document fed by upper- separation in a document reading-out part.

After a document (d) fed by upper-separation from a document stacker A is read out on a platen 10, the document (d) is discharged to a paper reverse-discharge part D so as to be reversely discharged onto a document re-stacker E. The preceding discharged document (d) from the platen 10 can be reversely discharged in the paper reverse-discharge part D during reading out a succeeding document (d). Thereby, the documents (d) are effectively exchanged on the platen 10, while the discharged document (d) can be facedown discharged onto the document re-stacker E. Accordingly, a discharged-paper stacker projecting from a device main body is not required, miniaturizing a device.