To enable quick and accurate registration by directly registering support data on a building design from business bases, and improve correspondence as the whole business concern by enabling the registered components to use even at other bases.

A center computer 1 owned by a management department associated with the building business is connected with a business base computer 2 owned by a plurality of business bases participating in the businesses, respectively, through a communication network 3. The center computer 1 comprises a database 4 for registering data, a registration means for executing registration work and a read means for reading data registered therein. The business base computer 2 is individually provided with a registration declaration means for newly registering and declaring data that are not registered in the database by communications with the center computer through the communications network, and a read means for reading registered data including the data registered in the database by communications from other business base computers.