An image forming apparatus such as a copier with a detachable process cartridge is provided with a first memory for storing the number of copying operations; a count renewing unit for increasing the count of the first memory and a second memory in the process cartridge, at each copying operation, a comparator for comparing the counts in the first and second memories, and a controller for determining a process condition specific to the process cartridge in case the counts do not mutually coincide. The service life of the process cartridge can be more precisely judged, and the process condition can be more appropriately determined for each process cartridge.