until the new process cartridge 3 is installed this process may be performed each power on time each time a toner end is detected or a life end of the photoconductive member is detected or each time after some action is taken based on the above detection if the new process cartridge 3 is installed and the check result of step s 55 is yes the cpu 2 c receives the monetary information from the em unit 5 of the new process cartridge 3 in step s 56 the cpu 2 c mainly receives the property information from the monetary information the property information includes a part number a manufacturing number and functional information which identify the process cartridge 3 the property information further includes price information indicative of a price of the process cartridge 3 in step s 57 the cpu 2 c verifies the property information received from the new process cartridge 3 with the property information of the previous process cartridge 3 contained in the configuration information which is stored in the memory 2 d and determines if the verification is successfully completed if the verification is successfully completed and the determination result of step s 57 is yes the process proceeds to step s 65 in which the cpu 2 c moves into the regular routine then the process ends if the property information of the new process cartridge 3 is not properly verified with the property information of the previous process cartridge 3 and the determination result of step s 57 is no the cpu 2 c sends an inquiry on the property information of the new.