To prevent occurrence of contradiction on address management due to duplication of log-on information attended with a switching time difference from data link communication channels in the data link communication system where communication is conducted with the data link communication channels is duplicate.

On the occurrence of channel switching on the side of a GES 30, an operating channel is switched from a GES channel A to a GES channel B. Since the channel is switched without deleting a relating processing of a computer repeater 40 due to an operation time difference between the GES 30 and the computer repeater 40, identification information and an aircraft number of a logical channel remain. The log-on information with respect to the same aircraft 10 is information again via the computer GES channel B. Then the computer repeater 40 registers a relating table to new log-on information, deletes the identification information and the information of the aircraft number of the old logic channel in this case and then registers the identification information and the aircraft number of a new logic channel after that.