To prevent interference between a transmission signal and a reception signal by increasing an attenuation of a transmission frequency band without increasing a passing loss at the transmission frequency band and a reception frequency band.

A transmission circuit 12 and a reception circuit 5 are connected to an antenna 3, wherein a transmission frequency band to which a channel of a transmission signal outputted from the transmission circuit 1 to the antenna 3 is selected close to a reception frequency band to which a channel of a reception signal received by the reception circuit 5 from the antenna 3 and an attenuation means 7 that attenuates the transmission frequency band signal is placed between the antenna 3 and the reception circuit 5.