PURPOSE: To eliminate a need to open a case of a machine on a road for the purpose of replacing elements or connecting a telephone line by rewriting beacon data in a storage means from the outside of this machine by radio.

CONSTITUTION: A CPU 22 adds a write permission code, which updates a memory part 11 in a beacon machine 3 on the road, to update data in a memory part 23 and transmits this data from an antenna 27 through a modulating part 24, an amplifying part 25, and a circulator 26. The machine 3 on the road receives updates data transmitted from a data update device 6 by an antenna 16 and writes data in the memory part 11 through a circulator 15, an amplifier 17, and a demodulating part 18 by a data write part 19 to update the memory part 11.