A relay device includes: an upper port configured to receive an upper packet containing audio data of a plurality of channels; a plurality of lower ports configured to output lower packets containing audio data of one or a plurality of channels; and a generation unit configured to reconstruct the upper packet to generate the lower packets. The plurality of lower ports include a first lower port and a second lower port. The first lower port is a starting point of a first network. The second lower port is a starting point of a second network and does not share nodes with the first network. The generation unit deletes audio data of a channel to be reproduced in the second network from the audio data contained in the upper packet, to construct audio data to be contained in the lower packet to be outputted from the first lower port.