PURPOSE: To surely suppress the rising of a temperature in a device by judging the actual rising of the temperature in accordance with the present and past use contents and a cooling time.

CONSTITUTION: A cooling blower 27 cooling an original platen 12 is arranged and the cooling time from the completion of the last copy to the start, of the next copy is counted by a control part 30. Residual heat energy is judged from the counted time and heat energy in the previous copy by a driving condition determining means 40. The heat energy in the present copy and the residual heat energy are integrated to deduce the actual temperature rising characteristic from the integrated heat energy. The blower 27 is driven at a revolving speed and by a driving time which correspond to the deduced temperature rising characteristic.