1. An information providing system to provide information of an information provider stored in a network server to an information seeker, the network server, comprising: a memory portion to store information of the information provider; a key conferring means to confer a security key to a first information seeker whom the information provider permits the access to his information, and to confer another security key to a second information seeker provided that the first information seeker permits the second information seeker to directly obtain information from the information provider; a key checking means to check whether or not the security keys fed by the first and second information seekers are authorized, and to determine whether or not information should be provided to the given information seeker; and an information searching/acquiring means to fetch information required by the first and second information seeker from the storage portion as nominated by the security key, wherein when the key conferring means finds that the first information seeker seeks the information from the information provider for a first time, the key conferring means assigns the judgment whether access of the first information seeker should be authorized or not to the information provider, when the key conferring means finds that the second information seeker seeks the information from the information provider for the first time, the key conferring means assigns the judgment whether access of the second information seeker should be authorized or not to the first information seeker, and the key conferring means confers the security key only to the authorized among the first and the second information seekers.