A recording medium carrier system of an image forming apparatus is constituted by independent units as a paper supply cassette (20), a paper feed unit (24, 31, 33), a transfer unit (12, 13), a fixing unit (50), and a paper ejecting unit (60). An intermediate transfer unit in the transfer unit is provided with an intermediate transfer belt (360) to which a toner image formed on a photoconductive drum (110) is primarily transferred at a primary transfer position and which secondarily transfers the toner image on a recording medium (S) at a secondary transfer position, and a driving roller (310) for circulating the intermediate transfer belt (360). The primary transfer position is arranged close to the driving roller (310).