An image forming system includes: a first and second stacking sections arranged at a position different from each other for stacking a sheet with an image formed thereon by an image forming section; a first conveyance path and a second conveyance path longer than the first one for conveying the sheet to the first and second stacking sections, respectively through a common conveyance path, wherein an interval between sheets fed along the common conveyance path is smaller than the difference between the second and first conveyance paths; a switching section for switching a conveyance path of the sheet conveyed along the common conveyance path between the first and second conveyance paths; and a control device controls such that an (N+1)th sheet is stacked on the first stacking section after the N-th sheet has been stacked on the second stacking section.