When copying control (copying/printing job) is finished, the main CPU checks whether the scanner control is being executed in the scanner portion. If the scanner control is not being executed, the main CPU checks whether there is any scanner control executing request. If there is no scanner control executing request, the main CPU locks a scanner control resource, reads out a count value of a toner residual amount stored in a non-volatile RAM, renews the control information of EEPROM of the toner cartridge through an interface, releases the lock of the scanner control resource and finishes the copying operation.