There is provided an image forming apparatus that can reduce the burden placed on the user by avoiding input errors and a complicated input operation when making settings for a color/black-and-white mixing operation and can perform a proper recovery even when a sheet determined to be abnormal is included in other sheets. Images are formed on sheets by an MFP 104 in accordance with an image forming job. The sheets on which the images have been formed are conveyed to a stacker tray 1207 detachably attached to the MFP 104. Information relating to the image forming job for the sheets conveyed to the stacker tray 1207 is written into a storage device 1202 provided in the stacker tray 1207.