PURPOSE: To perform adequate fixing operation even if toner is deposited and caked, by detecting the temperature of a fixing roller, and controlling the operations of the fixing roller and a fixing operation assisting means in accordance with the result of comparison with set temperature.

CONSTITUTION: With a power switch 29 turned on, an energizing signal from a fixation control means 15 is supplied to input switches 161 and 241 until the surface temperature of a fixing roller 6 obtained by a temperature detector 20 reaches set temperature, and respective solenoids are driven to separate the fixing operation assisting means composed of a peeling pawl 9, a cleaning blade 19, etc., from the roller 6, which turns without any fault. When the surface temperature reaches the set temperature and the toner deposited and caked on the roller 6 is fused and softened, the roller 6 and fixing operation assisting means are controlled to operation states to perform fixation treating operation without any hindrance even if the toner is deposited and caked.