To provide a technique capable of contributing a reduction of user's uncomfortable feeling caused by noise while maintaining double-sided productivity in an intra discharge type image forming apparatus that uses an ADU to perform image forming processing for both sides of a sheet.An intra discharge type image forming apparatus that uses an ADU to form an image onto both sides of a sheet and discharges the sheet on which an image has been formed to the vicinity of the center of the apparatus comprises: a sheet type information acquisition section 101 that acquires information concerning a bending rigidity of a sheet to be subjected to double-sided printing in the image forming apparatus as sheet type information; and a feed controller 102 that controls a sheet feed speed in a switchback feed section for sheet switchback feed and ADU based on the sheet type information acquired by the sheet type information acquisition section such that the higher the bending rigidity of a sheet, the lower the sheet feed speed.