To provide an AF-track circuit monitoring device capable of constantly monitoring an AF-track circuit in order to alleviate the maintenance work and of quickly clarifying the cause at the time of an occurrence of abnormality.

An AF-receiver 5 extracts only a signal, which has the desired frequency necessary for its own motion, by the aid of a BPF 5a out of input signals coming from a track 1 so as to output it to a receiver monitoring terminal 6. The level of this signal is monitored by an incoming voltage monitoring circuit 6a, while the frequency of the signal is measured by a frequency measuring circuit 6b, and the result is notified to a central monitoring device 13 via a network 12. The central monitoring device 13 notifies the frequency to a transmitter monitoring terminal 7. A digital filter 7a extracts only the signal, which has the same frequency component as that notified from the central monitoring device 13, out of signals inputted from the track 1 by an AF- transmitter 4 so that the level of this signal is monitored at a transmit level monitoring circuit 7b.