PURPOSE: To reduce the stress of an intermediate transfer belt and to suppress shaving or crack of its end so as to prolong the life of the intermediate transfer belt by positioning the intermediate transfer belt over the entire length in the lateral direction and turning it by a backup roller which presses it to a secondary transfer roller.
CONSTITUTION: The intermediate transfer belt 2 is movably supported in a state where it is allowed to float with a fixed air pressure jetted from plural small holes 15 which are provided all over the area of supporting surfaces of supporting shafts 14a-14d opposed to the belt 2, and bank-like guide parts 16a and 16b are protrusively provided over the entire length on both side parts of the belt 2 so as to position the belt 2 in the lateral direction by engaging the guide parts 16a and 16b with a positioning means 17 being the level difference or the groove of the supporting shafts 14a-14b, then the belt 2 is turned by the rotation of the secondary transfer backup roller 18 which presses the belt 2 to the secondary transfer roller 8. Since the belt 2 is allowed to float from the supporting shafts 14a-14d with the air pressure, they do not directly come in contact with each other and the shaving or the crack of the end are prevented from occurring.
KOIKE SHUJI
ISHII AKIHIKO
