An image forming apparatus includes a plurality of image forming stations for forming a toner image having superposed toner image components on a recording material, a fixing portion for fixing the toner image on the recording material, and a glossiness treatment unit, operable when a glossiness treatment mode is selected, for glossiness treatment of the toner image fixed on the recording material by heating the toner image. The glossiness treatment unit includes a film movable in a feeding direction of the recording material, a heating member contacting the film, and a pressing member cooperating with the heating member to form a nip, with the film therebetween, for nipping and feeding the recording material. In the glossiness treatment mode, one of the image forming stations forms, as a topmost layer, a toner image having a tone gradation provided by a dot growth type screening, and an image forming station, other than the one for forming the topmost toner image, forms the toner image having the tone gradation provided by a line growth type screening.