A relay device includes a receiver that receives facsimile transmission instructions via a private network from a client device that does not include facsimile transmitting functions, a facsimile communication unit that transmits a facsimile externally via a public network, on the basis of the facsimile transmission instructions received by the receiver, a determiner that, on the basis of the content of the facsimile transmission instructions received by the receiver, determines whether or not to request another device connected via the private network to execute facsimile transmission, and a requester that, in the case where the determiner determines to request another device to execute facsimile transmission, sends a transmission request regarding some or all of the facsimile transmission instructions received by the receiver to another device.