To provide an image forming device, a cartridge attachable to and detachable from the device and a display system for amount of cartridge used for reporting information for enabling a user to concretely judge how long the cartridge can be continuously used more and when a spare cartridge is to be prepared.

This device has a means 21 for storing a date, when the use of a cartridge B is started, in a storage means 20, a means 21 for storing the date, when the use of the cartridge B is started, out of the storage means 20 and a means 22 for statistically calculating information on the amount of the cartridge used peculiar to the user while using the date, when the use of the cartridge B is started read out of the storage means 20, the present date and information on the amount of the cartridge used.