PURPOSE: To obtain the reproduction signal with fidelity, by automatically selecting suitable signal pass band width in each reception, through the use of the modulation signal including the pilot signal representing multiplex signal or monaural signal, in the broadcast waves at transmission of multiplex signal.

CONSTITUTION: If the modulation signal is a monaural signal, the pilot signal is not detected at the detection circuit 7, and the selection signal of the output from the detection circuit 7 sets the selection characteristics of the intermediate frequency amplifying circuit 4 in a narrow band in this case. When the pilot signal is detected at the detection circuit 7 in receiving multiplex signal, the selection signal sets the intermediate frequency amplifying circuit 4 at a broad band. Further, for the stereo signal as a multiplex signal, taking left and right as respectively L and R, (L+R) signal is amplitude-modulated and (L-R) signal is frequency-modulated. After they are detected at the detection circuits 5, 6, independent L and R signal are obtained via a suitable matrix circuit.