the drum 1 the synchronization roller 12 is positioned so as to appear also in the third passageway 11 and serves to transport a document from the drum 1 to an appropriately disposed discharge tray 15 follower rollers 13 and 14 are provided opposite to the synchronization roller 12 respectively in the second and third passageways 10 and 11 in the second passageway 10 there is provided a detector 16 for detecting the motion of a document which is being transported therethrough as shown in fig2 and 3 this detector 16 has an arm 17 protruding into the second passageway 10 so as to detect not only a document being transported to the drum 1 but also a document being transported from the drum 1 the arm 17 is supported rotatably around an axis 18 such that it can rotate in the direction of the second passageway 10 a magnet 19 is attached to the arm 17 on the side away from the second passageway 10 and there is provided a lead switch 20 opposite to this magnet 19 when a document passes inside the second passageway 10 and the arm 17 is caused to rotate in the direction of a or b as indicated by arrows in fig2 the magnet 19 moves away from the lead switch 20 and thereby activates the lead switch 20 to detect the passage of a document in the second passageway 10 this detector 16 is utilized for controlling the motion of the synchronization roller 12 such as rotation in a normal direction rotation in a reverse.