An automatic document conveyer comprising a moving frame turnably mounted on a machine housing via a hinge mechanism and a conveyer belt mechanism mounted on the moving frame. The conveyer belt mechanism includes a support frame, a drive roller and a driven roller arranged in the support frame, and a conveyer belt wrapped round the drive roller and the driven roller. The support frame of the conveyer belt mechanism is so supported as to be moved by a predetermined amount toward the side opposite to the hinge mechanism while the end of the conveyer belt on the side of the hinge mechanism reaches to the closed position after having come in contact with the transparent plate at the time when the moving frame is turned toward the closed position.