When a user inputs a search condition, an agent sends, to a database of each organization to which the user does not have an access right, a search request including the search condition and the ID of a cooperation participant member having an access right to the database of the organization. A proxy of each organization causes the search device to search for a chain of links that connect between a data element that meets the search condition in the search request from the agent and a data element that represents the cooperation participant member in the search request, and returns to the agent information on a cooperation participant member that may have access to the data element that meets the search condition on the basis of the search result.