A relay device comprises: a routing controller configured to perform learning of routing information, which includes area information used to identify a relay area of communication packets and a network address of one or more other relay devices, and to determine a relay route of the communication packets, based on the learnt routing information; and a relay module configured to send the communication packets received by the relay device to a destination address of the received communication packets, based on the determined relay route. When the relay device receives a disaster notification packet notifying of a disaster area and when the determined relay route includes the disaster area, the routing controller changes the relay route to an alternative relay route that does not include the disaster area.