A gateway device that connects a base station to a core network, comprising: a communication unit that receives from a mobile management server in said core network a first key that deciphers ciphering that was set in a non access stratum, NAS, message that was received from a terminal that is subordinate to said base station, wherein a packet data network, PDN, is connected to said core network; said gateway device further comprising: a memory unit that stores a correspondence table that indicates, for each said terminal, the necessity or lack thereof of offloading to the PDN according to an access point name, APN, that is contained in the PDN connection request message transmitted as the NAS message from that terminal; wherein a processing unit: upon reception of the NAS message from said terminal, uses the first key to decipher ciphering that was set in the NAS message that was received from said terminal; and when the NAS message that was received from said terminal is a PDN connection request message, determines the route of a PDN connection based on the APN contained in the PDN connection request message and the necessity or lack thereof of offloading according to the APN that is indicated in said correspondence table. a communication unit that receives from a mobile management server in said core network a first key that deciphers ciphering that was set in a non access stratum, NAS, message that was received from a terminal that is subordinate to said base station, wherein a packet data network, PDN, is connected to said core network; said gateway device further comprising: a memory unit that stores a correspondence table that indicates, for each said terminal, the necessity or lack thereof of offloading to the PDN according to an access point name, APN, that is contained in the PDN connection request message transmitted as the NAS message from that terminal; wherein a processing unit: upon reception of the NAS message from said terminal, uses the first key to decipher ciphering that was set in the NAS message that was received from said terminal; and when the NAS message that was received from said terminal is a PDN connection request message, determines the route of a PDN connection based on the APN contained in the PDN connection request message and the necessity or lack thereof of offloading according to the APN that is indicated in said correspondence table. a memory unit that stores a correspondence table that indicates, for each said terminal, the necessity or lack thereof of offloading to the PDN according to an access point name, APN, that is contained in the PDN connection request message transmitted as the NAS message from that terminal; wherein a processing unit: upon reception of the NAS message from said terminal, uses the first key to decipher ciphering that was set in the NAS message that was received from said terminal; and when the NAS message that was received from said terminal is a PDN connection request message, determines the route of a PDN connection based on the APN contained in the PDN connection request message and the necessity or lack thereof of offloading according to the APN that is indicated in said correspondence table. upon reception of the NAS message from said terminal, uses the first key to decipher ciphering that was set in the NAS message that was received from said terminal; and when the NAS message that was received from said terminal is a PDN connection request message, determines the route of a PDN connection based on the APN contained in the PDN connection request message and the necessity or lack thereof of offloading according to the APN that is indicated in said correspondence table.