Patent ID: 8095021

Claim:
An image forming device to which can be installed an image forming material cartridge which contains an image forming material, and which has a non-volatile memory from which data can be read and to which data can be written, comprising: a counter which approximately counts the image forming material usage amount of the image forming material cartridge, and generates an image forming material usage amount count; a state detector which detects a predetermined state in which it is inferred that the amount of the image forming material in the image forming material cartridge is low; a storage unit which stores amount of change information which specifies the amount of change of the image forming material usage amount count from the time point that the predetermined state was detected until the present in the non-volatile memory of the image forming material cartridge; and a determination unit which determines that the image forming material cartridge is a refilled product when the amount of change of the image forming material usage amount count is larger than a first threshold value.