A transfer unit for use in an image forming apparatus includes a transfer belt, and a counter member. The transfer belt, having a given circumferential length, receives an un-fixed image, formed of an image developer, from an image carrier at a first nip, which is defined between the transfer belt and the image carrier. The counter member faces the transfer belt to form a second nip with the transfer belt. The un-fixed image is transferred from the transfer belt to a recording medium passing through the second nip. A slack portion is generated in the transfer belt, when a front edge of the recording medium passes through the second nip. The slack portion of the transfer belt being generated in a first portion of the transfer belt returning from the second nip to the first nip.