There is described an image forming apparatus, which forms high quality images free from a phenomenon of inter-sheet adhesion. The image forming apparatus includes a conveyance section to convey the transfer material along a conveying path; a cooling device disposed along the conveying path to cool the transfer material just after the toner image is fixed with heat; a controller-to control the conveyance section and the cooling device; and a first transfer-material detecting device disposed at a position adjacent to and upstream from the cooling device, in order to detect the transfer material coming into the conveying path. When the first transfer-material detecting device detects the transfer material coming, the controller controls the conveyance section to decelerate a conveyance velocity of the transfer material to a decelerated velocity lower than a normal conveyance velocity, so that the transfer material passes through the conveying path at the decelerated velocity.