IMAGE FORMING APPARATUS

PROBLEM TO BE SOLVED: To effectively use a fan for cooling a sheet even when a sheet processing device is added to expand a function.SOLUTION: An image forming apparatus 1 includes: a device body 1A with a lateral internal space part 42 with an open side part; a discharge roller pair 41 arranged in the device body to discharge a sheet with an image formed in the device body to the internal space part; a sheet cooling fan 48 for supplying air to the internal space part; and an air guide plate 61 which can be mounted on/dismounted from a bottom part of the internal space part, and guides air of the sheet cooling fan into the device body when mounted on the bottom part. The air guide plate 61 supplies air of the sheet cooling fan 48 into the device body, to effectively use the sheet cooling fan 48.