A communication control method which performs route control in a communication system, the communication control method comprising: a specific network constituting the Internet; a first network configured to accommodate a specific device connected to the specific network; a second network provided between the specific network and the first network; a network configured to accommodate a processing device which is connected to the second network; and the processing device configured to perform predetermined processing on the basis of a packet transmitted between the specific network and the first network: wherein the communication control method comprises: controlling a path in the second network in accordance with first routing information defining a path leading from the first network to the specific network; wherein the path comprises either a first path of the path leading from the first network to the specific network set as a path leading to the specific network via the network, or a second path of the path leading from the first network to the specific network set as a path leading to the specific networl via the second network and without passing through the network; the communication control method further includes forming a tunnel between a router device of the second network and a router device of the network, and controlling a transferring of a packet to the router device of the network according to the information in the packet sent from the specific device, by transferring the packet to the second path if a source address of the packet does not correspond to the specific device, or transferring the packet to the first path via the router device of the network and through the tunnel if the source address of the packet corresponds to the specific device; wherein the communication control method further comprises performing security processing in the processing device; as a result of the security processing, when it is determined that the packet is a valid packet, the processing device transfers the packet to the specific network via the second network; and when it is determined that the packet is not a valid packet, the processing device discards the packet. controlling a path in the second network in accordance with first routing information defining a path leading from the first network to the specific network; wherein the path comprises either a first path of the path leading from the first network to the specific network set as a path leading to the specific network via the network, or a second path of the path leading from the first network to the specific network set as a path leading to the specific networl via the second network and without passing through the network; the communication control method further includes forming a tunnel between a router device of the second network and a router device of the network, and controlling a transferring of a packet to the router device of the network according to the information in the packet sent from the specific device, by transferring the packet to the second path if a source address of the packet does not correspond to the specific device, or transferring the packet to the first path via the router device of the network and through the tunnel if the source address of the packet corresponds to the specific device; wherein the communication control method further comprises performing security processing in the processing device; as a result of the security processing, when it is determined that the packet is a valid packet, the processing device transfers the packet to the specific network via the second network; and when it is determined that the packet is not a valid packet, the processing device discards the packet.