PURPOSE: To prevent the extinction of storage data due to the consumption or the exchange of a battery by providing a power source connecting terminal to be inserted into a terminal with a data terminal.

CONSTITUTION: When a card is single, a prescribed power is supplied from a potential holding part 5 to a memory part 4, and a storage content is held in the memory part 4. The terminal into which the card is inserted is equipped with a pin bearing terminal structure into which a data terminal 1 and a power source connecting terminal 2 of the card are inserted. At the time of inserting the card into the terminal, and writing data in the memory part 4 or reading the data from the memory part 4 at the terminal, the power for operating a reading/writing circuit 3 and the memory part 4 is supplied from the terminal, and the potential holding part 5 is charged. Thus, only the power to the memory part 4 when the card is single is supplied from the potential holding part 5 so that a power consumption can be reduced, and the potential holding part 5 is charged every time the card is inserted into the terminal so that the consumption or exchange of the battery can be unnecessitated, and the storage data of the memory part 4 can be always held.