A wireless IC tag (11) is mounted to a toner cartridge (1), and a reader writer (2) reads and writes data from and to the wireless IC tag (11). The toner cartridge (1) includes plural cartridge contact terminals (12), and a load (13) arranged between the cartridge contact terminals (12). The load (13) corresponds to a type of the wireless IC tag (11). The reader writer (2) includes an antenna coil (21) for wireless communication with the wireless IC tag (11), and plural reader writer contact terminals (22) that contact to the plural cartridge contact terminals (12) respectively when the toner cartridge (1) is mounted to this image forming apparatus. Further, a wireless transmission characteristic of the reader writer (2) is adjusted in accordance with the load (13) electronically connected to the reader writer contact terminals (22).