To make a memory unit durable against the contact pressure with an external terminal and enable an IC memory to be used again after use.

The memory unit 5 consists of a circuit board 20 and the IC memory 21. The IC memory 21 is fixed on the circuit board 20, and a terminal of the IC memory 21 and the circuit board 20 are mutually joined by wire bonding. Then, potting treatment is done, and a face on which the IC memory 21 of the circuit board 20 is fixed is covered with a resin material 40. A surface of the resin material 40 is formed by a flat face. When the memory unit 5 is mounted, it is fixed in a mounting part 3 on an upper face of a cartridge case 3 by direction a face on an IC memory 21 side downward so that the upper face of the cartridge case 3 and an upper face of the circuit board 20 are at substantially same height. At this time, the resin material 40 is brought into contact with a rib 10 formed in the mounting part.