Abstract: A reader/writer (RW) requires identification of anti-collision techniques used by IC cards (A, B, C, and D). The IC cards implement answers to the anti-collision technique identification requirement by the reader/writer at different timings respectively for respective IC cards among the IC cards which use different anti-collision techniques respectively. The reader/writer requires identifications of types of the IC cards in dependence upon the anti-collision techniques in response to the answers by the IC cards. The IC cards return identification data thereof in response to the card type identification requirements by the reader/writer for respective IC cards among the IC cards which use different anti-collision techniques respectively. The reader/writer identifies the types of the IC cards in response to the identification data of the respective IC cards.

Abstract: A reader/writer (RW) requires identification information pieces of respective plural IC cards (A, B, C). The plural IC cards return the respective identification information pieces in response to the requirement by the reader/writer. Logical addresses are assigned to some IC cards among the plural IC cards respectively to cause the reader/writer to select them in response to the return of the identification information pieces by the plural IC cards. The IC cards selected by the reader/writer are controlled. The reader/writer cancels the assignment of the logical address to one of the selected IC cards. The logical address, the assignment of which has been canceled by the reader/writer, is assigned to an IC card among the plural IC cards to which any logical address has not been assigned yet. The IC card to which the logical address has just been assigned is controlled.

Abstract: A reader/writer (RW) requires identification information pieces of respective plural IC cards (A, B, C). The plural IC cards return the respective identification information pieces in response to the requirement by the reader/writer. Logical addresses are assigned to some IC cards among the plural IC cards respectively to cause the reader/writer to select them in response to the return of the identification information pieces by the plural IC cards. The IC cards selected by the reader/writer are controlled. The reader/writer cancels the assignment of the logical address to one of the selected IC cards. The logical address, the assignment of which has been canceled by the reader/writer, is assigned to an IC card among the plural IC cards to which any logical address has not been assigned yet. The IC card to which the logical address has just been assigned is controlled.

Abstract: An object of the present invention is able to provide an IC card in which for example, even if a state should occur in which a plurality of IC cards are piled up in any direction for use, a received signal is not greatly lowered but a normal usage pattern is secured. When the IC cards are piled up with the contours united, a projection drawing of an antenna of one IC card to an antenna surface of the other IC card has an area not overlapped at least 15% or more of an area having an antenna to the other antenna surface on the projection surface and the IC card can work.