To reduce the cost of a communication network system for covering areas over wide range requiring a plurality of base stations.

Communication networks N1 and N2 are constituted by providing a plurality of wayside radio equipment 111-11n and 141-14n, base radio equipment 12 and 15 and one base device 13 and 16 for controlling/managing communication between the base radio equipment 12 and 15 and on board radio equipment in a train 1 inside control zones for every control zones Z1 and Z2. Then, a specified communication term for radio communication with the communication network N2 in the adjacent control zone Z2 is provided within one cycle in the communication operation of respective communication networks N1 and N2 and during this communication term, bidirectional radio communication between both the communication networks N1 and N2 is enabled while switching frequencies to be used for both the communication networks N1 and N2 into the same frequency.