An image forming apparatus includes: an image forming device configured to form a toner image on a sheet; a fixing device configured to fix the toner image formed on the sheet by the image forming device at a nip; an executing portion configured to execute an operation in a cleaning mode for cleaning the fixing device by forming a predetermined toner image on a sheet using the image forming device and then by introducing the sheet into the nip; and a notifying device for notifying an operator that a maximum-width sheet usable in the image forming device is to be used in the operation in the cleaning mode.