When a special relationship is present between IC card owners, authority of one of the IC card owners cannot be easily given to the other owner of the IC card. However, an IC card of a second owner can issue a public key certificate of the IC card of a first owner so that the IC card of the first owner can be recognized as a child card of the IC card of the second owner. Thus, the first generation card authenticated by a route authentication station is set as an ancestor which can generate a descendent card which receives the authentication. By checking which parent card has issued the public key authentication owned by the child card, it is possible to given the authority of the parent card to the child card.