Abstract: A data storage means stores data in a predetermined information form. An information retrieval means retrieves the data stored in the data storage means. A reception means receives an information disclosure demand from a demander, a response rule storage means for storing general knowledge for generating a response responding to the demander and a personal relationship information associated with a unique personal relationship between a user having the data on an information provider side and a user on an information demander side. A response plan formation means, responsive to the demand received by the reception means, plans a response for exhibiting, to the information demander, data obtained by causing the retrieval means to retrieve the data stored in the data storage means on the basis of the knowledge and the personal relationship information stored in the response rule storage means.