A radio device includes an array antenna including a plurality of antennas; an adaptive array processing unit multiplying signals provided from the respective antennas of the array antenna by receive weights, and thereby extracting a signal received from desired another radio device; a switch circuit provided corresponding to at least one of the plurality of antennas for providing the signal received from the corresponding antenna to the reception signal processing unit in a receive operation; and a transmission amplifier amplifying and providing a modulated transmission signal to the first switch circuit corresponding to the one of the plurality of antennas.