PURPOSE: To prevent malfunction of antenna changeover at a weak electric field by selecting an antenna having a larger gain when the electric field strength becomes smaller than a scheduled strength.

CONSTITUTION: A signal meter output voltage is extracted from an intermediate frequency amplifier circuit 5, and the signal meter output voltage with its high frequency component eliminated therefrom by a low pass filter 12 is supplied to a comparison selecting circuit 14 and compared with a setting voltage Vo obtained by an electric field voltage setting resistor 13. When a signal representing a weak electric field is supplied from a comparison selecting circuit 14 to a selection discrimination means 10, the selection discrimination means 10 disregards an antenna switching signal coming from an AM detection means 9 to select the main antenna 1a with a high gain fixedly. Thus, the main antenna 1a is always used at a weak electric field and malfunction of receiving a signal with a small gain antenna, is evaded.