1. A cartridge life detecting system which detects and manages the life of a cartridge by mounting a memory on a print cartridge comprising at least an image formation member removably mounted on a main body of an image formation apparatus, carrying out operation to obtain information about the life of said cartridge based on contents read from said memory and criterial information of the life of said cartridge, and writing said information about the life in said memory, comprising the steps of: setting a value corresponding to the life of said cartridge by selecting one of a) combination of the number of printed sheets and the number of rotations of said image formation member, combination b) of the number of printed sheets and the number of pixels of image information, and c) combination of the number of printed sheets, the number of rotations of said image formation member and the number of pixels of image information; storing said value in said memory in advance; and making determination as to the life of said cartridge based on said value.