A distributed data base system is formed by terminal units connected in a public network or a private network. Each terminal unit stores respectively the real data and a temporary center for storing the one or a plurality of control information among various pieces of control information, such as contents corresponding to each real data, keyword or command assigned to data. Moreover, check information set up for acquiring security is provided as the one of the terminal unit. A terminal unit utilizing data obtains identification information of terminal units storing relevant real data by inputting contents, commands or keywords by accessing the center and reading or extracting the necessary real data through the network from a terminal unit having real data based on such identification information but is capable of restricting users (terminal units) which are allowed to read the open data in accordance with the degree of importance of the data.
This center, when it is assigned to the one terminal unit forming a distributed data base system, executes the control by gathering necessary control information from each terminal unit. This center having control information may be realized by the one terminal unit, but a center may also be provided individually corresponding to the items of information to be controlled. Moreover, the center may be established in one terminal unit and the center may be changed to the other terminal unit from the one terminal unit.