A image forming system that can prevent a toner from coming off while reducing the amount of consumption of a clear toner in binding sheets into a book. An image forming apparatus 100 forms an image on a sheet. A clear coating apparatus 200 forms a clear coating image on the sheet using the clear toner that becomes transparent after fixing. A bookbinding apparatus 600 connected to the image forming apparatus 100 and the clear coating apparatus 200 subjects the sheet to folding process. A job controller 501 and an image controller 502 cause the clear coating apparatus 200 to form the clear toner image at a folding position on the sheet in response to designation of a folding mode in the bookbinding apparatus 600.