In an antenna supervising apparatus for supplying a multiplexed signal comprised of a plurality of carrier wave signals respectively outputted from a plurality of transmitters through a transmission line to an antenna, a directional coupler detects progressive signals of the multiplexed signal to the antenna and the reflected signals thereof from the antenna, and a band-pass filter respectively filters the progressive signal and the reflected signal of one carrier wave signal preselected among those of the detected multiplexed signal. Further, a detector respectively detects the filtered progressive signal and the filtered reflected signal of the one carrier wave signal, and a micro processing unit calculates a standing wave ratio with respect to the preselected one carrier wave signal based on the detected signals.