A radio receiver includes a down-converter 110 for receiving a radio multiplexed signal containing a first signal and a second signal, multiplying the first signal and the second signal by a mixer 104 to thereby down-convert the radio multiplexed signal and generate an intermediate frequency signal 5e. The mixer 104 has a control section for controlling an operating bias of the mixer 104 in response to a signal strength of at least either one of the first signal or the second signal. Thus, the dynamic range of the mixer can be widened so that stable image characteristics can be obtained over a wide range of transmission distance.