PURPOSE: To separate satisfactorily transfer paper, and also, to pevent a toner image from being retransferred to a photoreceptor from transfer paper, by superposing and impressing DC voltage and AC voltage to a corona wire of a separating charger, and also changing the DC voltage by the time when flash light is emitted, and other time.

CONSTITUTION: As for a voltage control means for changing DC voltage, an output state of a timing circuit 13 is controlled by on (close) and off (open) of a paper detecting switch 10 between a photoreceptor 1 and a fixation device 9, and its output is provided to a trigger pulse generating circuit 15 from a timing pulse generating circuit 14, and also is provided to a xenon lamp 9a through a xenon lamp power supplying circuit 16. An output of the timing pulse circuit 14 is provided to a separate voltage switching timing circuit 17, too, and is provided to a corona wire 7a of a separating charger 7 from a separating charger power supplying circuit 18. The separating charger power supplying circuit 18 consists of an AC power source 18a for impressing AC voltage to the corona wire 7a of the separating charger 7 and a DC power supplying circuit 18b for impressing DC voltage, and a changeover switch 18c for changing DC voltage impressed to the separating charger 7 is provided on the DC power supplying circuit 18b, and is operated by high and low output voltage of the separate voltage switching timing circuit 17.