An object of the present invention is to provide an image forming apparatus using simultaneously transferring and fixing means and capable of reducing time unable to perform image formation due to temperature change of an image bearing member, the apparatus including: a rotatable image bearing member; electrostatic image forming means capable of continuously forming electrostatic images on the image bearing member based on forming image amount information; toner image forming means for developing the electrostatic image on the image bearing member and forming a toner image; primary transferring means for transferring the toner image on the image bearing member to a rotatable intermediate transferring member; simultaneously transferring and fixing means for transferring the toner image on the intermediate transferring member to a recording material and heating and fixing it; image bearing member detecting means for detecting temperature of the image bearing member; and starting means for starting electrostatic image formation of the electrostatic image forming means based on a detection result of the image bearing member detecting means and the forming image amount information.