PURPOSE: To prevent tone occurrence of a failure and the degradation of an image in accordance with the rise of a temperature by transiently stopping a printing action and executing controlling for evading rising the temperature in a device, when a deviation from a specified temperature condition is detected.

CONSTITUTION: A temperature sensor 1 is installed on a laser unit 2 as the light emitting part of a laser scanner as an exposing device. When the temperature of a laser diode is risen above a guarantee temperature, the life of the laser diode is remarkably shortened in proportion to the temperature. When the temperature in a machine is risen because the using form of a user is improper and heat is not radiated outside the machine, for evading the rising of the temperature, the temperature sensor 1 is directly arranged on t laser unit 2 including the laser diode and a warning signal is generated from a temperature rise warning circuit 9 based on information detected by the temperature sensor 1, to transiently stop the next printing and simultaneously, turn off the heater of a fixing device, so that a ventilation fan is rotated at full speed and controlled so as to suppress the rising of the temperature in the machine.