Disclosed herein is an access privilege transferring method for safely transmitting privilege information about each object between subjects (users) over an object space in which service objects are scattered. User information and secret information of clients are shared between the clients and servers. A client that transfers privilege information generates privilege information weakened in its own contents of privilege. Further, the client applies a one-way function or an encryption function to a bit string obtained by joining the generated privilege information and the secret information to each other, thereby generating protected privilege information with which a third party who does not know the secret information is not capable of tampering. Utilizing the protected privilege information makes it possible to safely transfer access privileges. Further, the server analyzes the protected privilege information by using the secret information to thereby make it possible to safely confirm whether a client that makes an object request is authorized.