PURPOSE: To shorten a warming-up time by detecting the heat output from a fixing heater roller with the aid of a temperature sensor, necessarily limiting a current impressed on the heater roller and continuously controlling the sequential leading edge of a scanner motor according to heat output monitor through the temperature sensor.

CONSTITUTION: The heat outputs from the upper heat fixing roller 7a and the lower heat fixing roller 7b respectively incorporating heaters 5a and 5b, 5c and 5d are detected with the aid of the temperature sensor 5. According to the detected outputs, a microcomputer 1 limits the currents impressed on the rollers 7a and 7b stepwise so as to control the generated heat capacity of the rollers 7a and 7b. Next, a heat output generated state is continuously monitored by the sensor 6 and the sequential leading edges of the scanner motors 3Y, 3M, 3C and 3BK are controlled through the computer 1 according to the heat output generated state. Therefore, the current necessary for the heating-up of the fixing heat roller to a reference temperature and the rush current necessary for the leading edge of plural scanner motors are effectively distributed in a rated current, so that the warming-up time of a printer can be drastically shortened.