Formerly, an individual communication operation was repeated between a dedicated terminal apparatus and other terminal apparatuses. Therefore, an extremely wide transmission band was required depending on the number of terminal apparatuses. The present invention transmits significant data unidirectionally among a plurality of terminal apparatuses and causes a terminal apparatus at the downstream end of a transmission path to collect the significant data. Each terminal apparatus includes a data detection section for detecting whether or not significant data written at another terminal apparatus located toward the upstream side of the transmission path is received, and also includes a data selection section for transferring the significant data as is to a downstream terminal apparatus when the reception of the significant data is detected or outputting significant data generated within the terminal apparatus to a downstream terminal apparatus when the reception of the significant data is not detected.