An image forming apparatus has a printing function, a scanner function, and a control unit. In the printing function, a printed material acquired by recording image data included in a printing job received through a network on a recording paper is discharged. In the scanner function, the image data is acquired by reading a manuscript. The control unit judges whether the scanner function is in use for a long time (step A2) at the time of receiving the printing job (step A1). A printed material is discharged to an in-body discharge tray when it is judged that the scanner function is not in use for a long time (step A3). The printed material is discharged to a side discharge tray when it is judged that the scanner function is in use for a long time (step A5).