PURPOSE: To facilitate the jam recovery with a simple constitution to perform the double-faced copy without page disorder, by correcting contents of a feed paper number counter to the value of an eject paper number counter only in case of the front face when a jam occurs.

CONSTITUTION: The transfer paper fed from a cassette 1 is transferred to a gate 17 and an auxiliary path 18 after the front face copy and is reversed and is carried to an intermediate tray 24 through a gate 27. This transfer paper is subjected to the rear face copy and is ejected to a copy tray 16. The next transfer paper is subjected to the copy processing similarly, and both-faced copies are ejected to the tray 16 without page disorder. The front face copy or the rear face copy during which a jam occurs is detected by a transfer paper detecting sensor 31 or 30 provided on carrying rollers 23 and 26 for trays 24 and 16; and only when the jam occurs during the front face copy, contents of a feed paper number counter are corrected to the value of an eject paper number counter, and thus, the number of copies is not disordered even in case of a jam during the rear face copy by a simple constitution, and the jam recovery is facilitated by recopy.