Image forming apparatus with change unit for changing temperature of fixing unit at time of actuating image forming unit

An image forming apparatus capable of performing can perform an image forming operation together with temperature rise by heating of a heat fixing apparatus operation to ensure a good fixability and a shortest short first print out time and to prevent loss of while minimizing power consumption without and not over-burdening a constitutional member of the image forming apparatus (e.g., life-shortening shortening the life of the constitutional member)is provided. The image forming apparatus includes an image forming unit and a fixing apparatus unit for heat-fixing a toner image on a recording material and a detection member for detecting a toner of a fixing apparatus member and performs simultaneously temperature rise by heating of the fixing apparatus and an image forming operation including a pre-process and an image forming sequence. In the image forming apparatus, a start A fixing temperature of the pre-process and a start temperature of the image forming sequence with respect to the fixing apparatus member are unit is made variable depending on whether full-color image formation is performed or mono-color image formation is performed.