To perform a monitor-run test of CTC or PRC without waiting for a new CTC station device to be installed.

A CTC updating device 50 comprises an old-line transmission unit 60 which is connected to an existing CTC line 22 and receives transmission messages of an old type, and a new line transmission unit 70 which is connected to a new CTC line 42 and receives/transmits transmission messages of a new type. The old line transmission unit 60 is made to extract transmission messages of indication information from all the transmission messages received. The new line transmission unit 70 is made to update the corresponding data in a station-state table including the data of the indication information of field facilities installed in each station according to the indication information of the transmission messages extracted by the old line transmission unit 60. Further, when transmission messages of polling are received via the CTC line 42, neglecting control information but responding to the request of the indication information, the transmission messages of the indication information is made in a new type manner according to the station-state table, and is returned via the CTC line 42. The monitor-run test is performed by interposing the CTC updating device 50 in both the new and old systems.