A relay device including: an information storage unit that stores conversion-target header information; a downlink signal dividing unit that divides a downlink signal received from the radio control device into a header and a payload; a signal replicating unit that makes the same number of copies of the payload of the downlink signal as the number of the plurality of destination radio devices; a downlink signal header information conversion unit that performs conversion on the header of the downlink signal for each destination radio device based on the header information stored in the information storage unit; and a signal addition assignment unit that adds the header converted by the downlink signal header information conversion unit to each of the payloads of the downlink signal replicated by the signal replicating unit, and transfers the payloads to the radio devices respectively corresponding thereto.