Automatic document conveying device

An automatic document conveying device (4) is provided in an image-processing machine (2) having a transparent plate (8) on which to place a document to be processed, the transparent plate (8) being disposed on the upper surface of a housing (6). The automatic conveying device (4) is provided with a document delivery re-introduction section (16) which sends a document delivered through a document introduction section (12) and a central main portion (14) selectively to a first document receiving tray (94), a second document receiving tray (128) or the transparent plate (8) by means of a branching means. The document delivery re-introduction section (16) is provided with a first branched passage (126) for sending a document into the first document receiving tray (94), a second branched passage (130) for sending the document into the second document receiving tray (128), and a re-introduction passage (132) for re-introducing the document onto the transparent plate (8). The document delivery re-introduction section (16) is provided with a first opening-closing member (176) for opening most of the first branched passage (126) and most of the second branched passage (130), and a second opening-closing member (200) for opening most of the re-introduction passage (132) in a state where the first opening-closing member (176) is held at an open position.