PURPOSE: To reduce noises and to improve the SN ratio by connecting a filter for attenuating one or more required received frequency bands or required broadcasting frequency bands selected from a specific place to a receiver.

CONSTITUTION: An antenna conductor is mounted on a glass plate of a rear window for an automobile, a received signal from the antenna conductor is sent to an AM radio 1 arranged in the vicinity of a driver's sheet through a coaxial cable, a channel is selected by the AM radio 1, and a speaker 3 arranged close to the glass plate of the rear window is driven by a low frequency amplifier part in the AM radio 1. In this case, a filter 2 for attenuating one or more required received frequency bands or required broadcasting frequency bands selected from inputs to the low frequency amplifier part in the receiver 1 is connected between the low frequency amplifier part of the receiver 1 and the speaker 3. Consequently an RF carrier component is attenuated and the probability of radiating the RF carrier component from a speaker cable, a power supply cable or the like as a radio wave can be reduced.