To improve availability of a data transmission line and to shorten the processing time for arrival confirmation by confirming the arrival of a transmitted frame based on the information of an error detection bit, an address recognition bit and a frame copy bit inside a frame to be returned to the transmission source corresponding to the transmitted frame.

In this ring local area network(LAN) with which (n) stations are connected through a transmission line to form a lop and data are transmitted between the respective stations corresponding to the frames, each station is provided with an arrival confirmation processing part. Then, the arrival of the transmitted frame is confirmed based on the information of an error detection bit, an address recognition bit and a frame copy bit inside the frame to be returned to a certain station corresponding to the frame transmitted from a certain station to the other station.