PURPOSE: To suppress a switching noise of an antenna system for antenna changeover diversity system.

CONSTITUTION: The system is provided with plural antennas 11a, 11b and an antenna changeover device 13 selecting an optional antenna of the plural antennas alternatively, which are interconnected by a transmission line and with a communication means having at least any of a receiver 16 and a transmitter 15. Then an antenna with a high average reception level is allocated in the plural reception antennas with priority through a controller 19 implementing antenna changeover and inhibit of antenna changeover based on a procedure programmed in advance.