PURPOSE: To provide a side tone suppressing device for SNG which suppresses the sound of a repeat destination reporter in an on-aired sound and generates a monitor sound easy to speak by the repeat destination reporter by subtracting a sound in which the sound of a repeat destination is delayed from an on-aired television sound especially in a communication system in which communication between a main station and the repeat destination is performed by using a communication satellite line jointly with a TV broadcast line.

CONSTITUTION: The communication system in which the communication between the main station and the repeat destination is performed by using the communication satellite line jointly with the TV broadcast line is comprised so that level difference and line distortion can be compensated by superimposing the same signal as a signal to be transmitted to the main station A, i.e., inputting the output of a fixed delay circuit 3 to an adaptive equalizer 4, and correcting the filter coefficient of an adaptive equalizer 8 adaptively so as to minimize an error signal (e) by the communication satellite line from which the signal is outputted to the delay signal of the repeat destination B mixed in a received TV signal via the fixed delay circuit 3 and the adaptive equalizer 4 provided between the transmitter 1 and a monitor receiver 2 when the signal transmitted from the repeat destination B to the main station A via the communication satellite line is transmitted again to the repeat destination B via the TV broadcast line and it is monitor-received by the repeat destination B.