A pre-5th-Generation (5G) or 5G communication system for supporting higher data rates Beyond 4th-Generation (4G) communication system such as Long Term Evolution (LTE), in which a method performed by a user equipment (UE) includes transmitting, to a first base station (BS), a packet data network (PDN) connection request message, receiving, from the first BS, information on a first single-network slice selection assistance information (S-NSSAI) selected by a combination of a packet data network gateway control plane entity (PGW-C) and a session management function (SMF) from among the UE's at least one subscribed S-NSSAI, transmitting, to a second BS, a registration request message including a requested NSSAI in which the first S-NSSAI is included, and receiving, from the second BS, a registration accept message including an allowed NSSAI in which a second S-NSSAI mapped to the first S-NSSAI is included.