There is provided an image forming apparatus including a fixing unit in which fixing temperature is calculated from a toner bearing amount and fixing processing is performed while reducing drop in the print speed. A method for controlling a temperature of a fixing unit for fixing a recording material onto a recording medium includes determining, for image data of a plurality of pages, whether a data size of the image data of a unit page is smaller than or equal to a predetermined threshold, and based on the determination result, selecting whether to control the temperature of the fixing unit to be a temperature determined from the amount of the recording material of the image data of the unit page, or to control the temperature of the fixing unit to be a predetermined temperature.