This system includes a changer data base, in which a changer registers his or her own new address, relationally storing a new address disclosing condition for an inquirer who wishes to know the new address of the changer, a disclosure judge judging whether to disclose the new address to the inquirer based on the new address disclosing condition when the inquirer inquirers about the new address with the presentation of an old address of the changer, and a discloser disclosing the new address of the changer to the inquirer if the disclosure judge judges that the new address is disclosed. Hence, various responses, with a high degree of freedom, can be made depending on a changer's intention when an inquiry about the new address after change of the changer is sent from an inquirer.