A sheet conveying device can selectively execute a first conveyance process of conveying sheets on a first tray and discharging the sheets onto a second tray, a second conveyance process of conveying the sheets on the first tray and discharging the sheets onto a third tray, or a third conveyance process of conveying the sheets on the third tray and discharging the sheets onto the second tray. A control device records conveyance history information indicating by which conveyance processes each of the sheets on the first tray has been conveyed in a storage device. Furthermore, the control device causes the sheet conveying device to sequentially select the first conveyance process or the third conveyance process for each of the sheets based on the conveyance history information and execute the selected process.