PURPOSE: To permit the respective users of different work stations connected to one common link to access to the content of other user activity and a present status by adopting the expression of a common structured data object. CONSTITUTION: In an office information system 10, the plural user work stations 14 containing the work stations 14A and 14B are connected to LAN 12. The other units of a network file server 16, a network file/mail/communication server 18, a printer server 20 and a printer 22 are connected to LAN 12. Then common structured data objects 40 exist on the disk tops 32 of the work stations 14A and 14B. The users of the different work stations can execute cooperative work on a real time basis with the data content of the related structured data object.