PURPOSE: To reduce an updating processing of duplicate data information by suppressing a concentration of a processing related to whether duplicate data of remote data exists in a local data base or not, and the traffic, in a distributed data base.

CONSTITUTION: In local data bases 14,..., 17 for constituting a part of a vertical distributed data base, in the case data is extracted from data 18 in the local data base 14, and stored as data 19 in the local data base 15, information for showing a relation of the data 18 and 19 is registered in both of management information 22 and 23. Between other data bases, as well, such registration of management information is executed, and in the case it is desired to know a relation of the data 18 and 20, the relation of the data 18 and 19 is derived by retrieving the management information 22, and moreover, the management information 23 is retrieved, and the relation of the data 19 and 20 is derived. By combining the derived two relations, the relation of the data 18 and 20 is derived.