An image forming system including: an image forming apparatus to perform fixing processing on a sheet based on setting information on a job, and outputs the sheet on which the fixing processing is performed; a humidification device to moisten the sheet outputted from the image forming apparatus, wherein the humidification device including: a pair of humidification rollers to contact with each other so as to form a nip part, and to moisten the sheet which passes through the nip part; a water-supply roller to contact with the humidification rollers so as to supply moisture to the humidification rollers; and a control section to perform dry control of the humidification rollers at a timing when the sheet does not pass through the nip part after the water-supply roller supplies the moisture to the humidification rollers.