An image forming system having: a sheet feeding unit which cuts a roll sheet and feeds cut sheets; a stack unit which stacks and stores the sheets fed by the sheet feeding unit and feeds the stored sheets; an image forming portion which forms an image on the sheets fed from the stack unit; and a controlling unit configured to control the feeding unit and the stack unit so that the stack unit feeds a sheet stored in the stack unit to the image forming portion when the sheet feeding unit feeds a sheet to the stack unit so as to stack the sheet from the sheet feeding unit into the stack unit.