PURPOSE: To attain the communication between the secondary stations and also the multiaddress calling communication to all stations including a primary station from the secondary station by relaying the transmission frames from the seondary stations by the primary station in the communication between the stations in a loop network by means of a polling system.

CONSTITUTION: A loop network communication method includes a transmitting destination address part 9a, a transmitting source address part 9b, and an information part 9c being the communication data. In the loop network communication of a polling system applying a transmission frame, a control area is provided in an information part 9c or 10c of the transmission frame. Then an identification flag identifies either of the communication between the primary and secondary stations, the communication between the secondary stations or the communication from a secondary station to all other stations. The transmitter address and the transmitting destination address are set in the control areas 9d and 10d respectively.