more than 0 8 the sphericiry u03c6 a diameter of the circle whose area equals the projected area of the particle a diameter of the circumscribed circle to the particle these are easily calculated by the steps of gathering the toner image on the slide glass magnifying the toner image 500 times by a microscope and measuring 100 of the toner images thereby it is possible to transfer the toner image from the intermediate transfer belt 2 to the transfer fixing roller 13 efficiently as disclosed in japanese published unexamined patent application no hei 9 2584747 according to the embodiment described above the toner image which is transferred from the intermediate transfer belt 2 to the transfer fixing roller 13 is heated without the record medium i e is heated before being transferred onto the record medium p and is heated until being fixed on the record medium p thereby the toner image can be sufficiently fixed onto the record medium p while being heated at a lower temperature when the record medium p is at the nip n compared to heating the toner image only when being transferred to the record medium p the results of experiments conducted by the present inventors show that with this operation the toner image fixed on the record medium is of a high enough quality when the heating temperature on the transfer fixing roller 13 is 110 u00b0.