A service is transparently provided to a mobile terminal device without the mobile terminal device knowing an address of a service providing device or a device which relays a packet in a network. A packet between the service providing device which provides a service and a mobile terminal device 10 which receives the service is relayed by a mobility control node 21. An access router 12 inquires of another device about information on the mobility control node 21, and holds correspondence information between information obtained by an inquiry result and identification information of the mobile terminal device 10 in a table. Transfer of a packet between the mobile control node 21 and the mobile terminal device 10 is controlled based on the correspondence information held in the table. With this configuration, the network can transparently provide the service to the mobile terminal device without the mobile terminal device knowing the address of the device which relays the packet in the network.