A relay device according to the present invention includes an uplink signal relaying unit that performs an uplink signal relaying operation that amplifies an uplink signal transmitted through an uplink channel from a mobile station and re-transmits the amplified uplink signal to a base station; a frequency information acquisition unit that acquires frequency information that represents a frequency band that said mobile station uses for the uplink channel periodically or at predetermined timings; an uplink signal detection unit that determines whether or not the average reception power of the uplink signal in the frequency band represented by the frequency information acquired by said frequency information acquisition unit exceeds a predetermined threshold; and a control unit that controls the uplink signal relaying operation performed by said uplink signal relaying unit based on a determined result of said uplink signal detection unit.