PURPOSE: To monitor an entire-screen type message completely by providing a means which analyzes and stores the contents of the entire-screen type message and edits a new message.

CONSTITUTION: All messages between a terminal 1 to be monitored and a command processor or user program 3 are reported from a terminal input/output control part 2 to a message transfer equipment 6 as monitoring messages. The transfer equipment 6 stores the monitoring messages in a message temporary storage device 8 and reports the generation of the monitoring message to a monitoring message display device 11 through a terminal monitoring event communication device 7. On receiving the report, the display device 11 performs processing such as the analysis and composition of the messages according to the kinds of the messages and then extracts and sends out messages to be displayed on a main monitor terminal 4 to the terminal 4 according to the indication of a time monitoring device 12.