An office information system has a plurality of work stations connected via a network to mutually exchange electronic mail, each work station including a control information definition unit for defining control information representing what kind of processing can be performed on mails after reception, a processing log memory unit for storing log information of operations which have been performed on received mail, a control unit for guiding a receiver by referring to both the control information and log information, a task tracking instruction unit for inquiring into the processing status of mail, and a task tracking unit for reporting the status in response to such a tracking instruction. The system stores and interprets control information relating to the flow of an OA object on the network, which has been conventionally involved in the memory of an office worker, and guides the office worker to work to be done by the office worker. As a result, the chance that the OA object will stagnate at a certain location is reduced, and the circulation of OA objects on the network is improved.