A document feeder configured to feed document sheets, comprising: a feed tray configured to be loaded with the document sheets to be fed; a catch tray configured to be loaded with the document sheets ejected thereon; a carrying path configured to guide the document sheets in a carrying direction from the feed tray to the catch tray via a scanning position where the document sheets are scanned; a reversal path configured to diverge from a diverging point on the carrying path and connect to a converging point on the carrying path, the diverging point being located downstream relative to the scanning position in the carrying direction, the converging point being located upstream relative to the scanning position in the carrying direction; a switchback mechanism provided on the reversal path, the switchback mechanism being.configured to convey a document sheet from the reversal path back to the converging point with a previous trailing end of the document sheet as a new leading end thereof in the carrying direction.; an ejection roller configured to eject the document sheets onto the catch tray; and an ejection mode switching mechanism having a flap provided upstream relative to the catch tray in the carrying direction in a manner movable up and down relative to the ejection roller, the ejection mode switching mechanism configured to, with the flap being moved up and down, switch an ejection mode between a first mode and a second mode, the first mode being an ejection mode in which the document sheets are sequentially ejected on a stack of already-ejected document sheets on the catch tray, the second mode being an ejection mode in which the document sheets are sequentially ejected and inserted under a stack of already-ejected document sheets on the catch tray, wherein a lower surface of the flap is configured to form part of the reversal path in the first mode. a feed tray configured to be loaded with the document sheets to be fed; a catch tray configured to be loaded with the document sheets ejected thereon; a carrying path configured to guide the document sheets in a carrying direction from the feed tray to the catch tray via a scanning position where the document sheets are scanned; a reversal path configured to diverge from a diverging point on the carrying path and connect to a converging point on the carrying path, the diverging point being located downstream relative to the scanning position in the carrying direction, the converging point being located upstream relative to the scanning position in the carrying direction; a switchback mechanism provided on the reversal path, the switchback mechanism being.configured to convey a document sheet from the reversal path back to the converging point with a previous trailing end of the document sheet as a new leading end thereof in the carrying direction.; an ejection roller configured to eject the document sheets onto the catch tray; and an ejection mode switching mechanism having a flap provided upstream relative to the catch tray in the carrying direction in a manner movable up and down relative to the ejection roller, the ejection mode switching mechanism configured to, with the flap being moved up and down, switch an ejection mode between a first mode and a second mode, the first mode being an ejection mode in which the document sheets are sequentially ejected on a stack of already-ejected document sheets on the catch tray, the second mode being an ejection mode in which the document sheets are sequentially ejected and inserted under a stack of already-ejected document sheets on the catch tray, wherein a lower surface of the flap is configured to form part of the reversal path in the first mode.