Cooperation system using open public network

The present invention relates to a cooperation system using an open public network providing a cooperation service between multiple enterprises comprising: a server for performing multiple processes for the cooperation service; a user terminal for limitedly using data generated by the multiple processes according to usage rights by accessing the server over the open public network; and a database for storing data generated by the multiple processes. The server performs the multiple processes including a project development process, a data change process, a general business process, and a cooperation process, and the server limitedly notifies the user terminal of events occurring while the multiple processes are performed according to usage rights. By applying IT technology, the system supports an improvement in constitutions of various manufacturing sector enterprises requiring delivery time shortening, cost reduction, and quality improvement in cooperation between enterprises regardless of types of business.