PURPOSE: To prevent a heat roll from overheat by providing the titled device with a means for detecting the temperature of the heat roll, a means for selecting the setting point of a timer and a power control means and increasing the time-up speed of the timer in accordance with the increase of the temperature of the heat rool when a main power supply is ON.

CONSTITUTION: The body 1 of the copying machine is provided with a platen 2, a photosensitive drum 3, a paper tray 4, and a fuser 5. A microprocessor is constituted of a CPU9, a read-only memory (ROM)10, a random access memory (RAM)11, and the timer 12. An ON/OFF power control device 13 supplies or interrupts electric power supplied from a power source 14 to/from a heat lamp 7 in accordance with a control signal outputted from the CPU9. Temperature data for discriminating the existing range of the heat roll 6 when the main power supply switch in the copying machine body 1 is turned on and the set point of the timer 12 which is set up in accordance with said temperature range are stored in the ROM10 or the non-volatile RAM11.