Provided is a service request method performed by an SMF device, including receiving, by an AMF device, an N2 message including a service request message from an access network, and receiving an Nsmf_PDUSession_UpdateSMContext request message including a PDU session ID and location information and an access type of a UE from the AMF device; verifying selection criteria of a UPF device based on the received location information of the UE and determining whether to use a new UPF device or an old UPF device; and sending an Nsmf_PDUSession_UpdateSMContext response message including information on a PDU session ID with the new UPF device or the old PUF device based on the determining. The access network is configured to receive, from the AMF device, an N2 request message including an MM NAS service accept and the access network is configured to perform a service through an RRC connection reconfiguration with the UE.