A toner consumption amount identifying unit identifies a toner consumption amount of toner consumed in a printing process from the print data. A toner residual amount identifying unit identifies a toner residual amount in a toner container from the toner consumption amount. A toner residual amount data managing unit stores order-timing toner residual amount data into a non volatile memory device at a timing when an ordering process of the toner container succeeds, and deletes the order-timing toner residual amount data in the non volatile memory device if the value of the toner residual amount is larger than a value of the order-timing toner residual amount data. An order processing unit performs the ordering process if the order-timing toner residual amount data is not stored in the non volatile memory device and the value of the toner residual amount is either equal to or less than a predetermined value.