control related to the purposes of the image forming apparatus the settings of the width and the using frequency of paper used for the determination of the cycle time can be input as modes of paper feed intervals by using the console panel 14 or set up switches incorporated therein in addition the results of determination of the cycle time are stored in the nvrams 13 and 23 etc this cycle time is used upon printing in steps st 7 and st 17 thus there is little possibility that the heating roller 7 becomes at a high temperature only at the end portions thereof even with the use of a wide paper and hence processing printing paper feeding etc can be performed at high speed at a setting of the calculated cycle time since there is a high possibility that the heating roller 7 becomes at a high temperature only at the end portions thereof for a narrow paper processing is performed at low speed at a setting of the calculated cycle time u03b1 so that a time margin is given to permit the temperatures at the central portion and the end portions of the heating roller 7 to approach each other through temperature control thereby to prevent them from exceeding the allowable range as a result.