PURPOSE: To decrease the titled system in cost by allowing each terminal device to set the 1st timer value to a timer depending on a terminal device number and an own terminal device number in a detected synchronizing signal and to set the predetermined 2nd time value when no data to be set exists at the acquisition of transmission right so as to eliminate the need for a controller.

CONSTITUTION: A timer 60 of a terminal device 101 is time-over at a time t2 elapsed by a time τ from a time t1 at first and outputs a timeup signal to a transmission/reception control section 87. In receiving the timeup signal, the section 87 acquires the transmission right and sends it to a timer setting section 86 when no data to be sent exists. In receiving it, the setting section 86 sets the predetermined 2nd timer value T2 to the timer 60. On the other hand, other terminals devices 102∼104 and 100 acquire the transmission right at a time elapsed by 2τ and 5τ from the time t1 respectively and a timer value T2 is set to the timer 60 when no data to be sent exists.