Provided is an image forming apparatus that includes a conveying section, an image forming section, a medium sensor, a mark printing section, and a controller. The conveying section is configured to convey a medium in a medium conveying direction. The image forming section is configured to form an image on the medium conveyed by the conveying section. The medium sensor is configured to perform detection of the medium conveyed by the conveying section. The mark printing section is configured to perform printing of a mark on the medium conveyed by the conveying section. The controller is configured to cause, based on a result of the detection by the medium sensor, the mark printing section to perform the printing of the mark on the medium, from a timing at which image formation on the medium by the image forming section is completed.