Registration method of user terminal in wireless communication system and apparatus therefor

A user equipment for performing policy update in a wireless communication system, the user equipment comprising:

• a transceiver configured to transmit and receive signals;
• and
• a processor configured to control the transceiver,
• wherein the processor is further configured to:
• transmits a first registration request message to an access and mobility management function (AMF),
• wherein the first registration request message comprises requested network slice selection assistance information (NSSAI) comprising single (S)-NSSAI corresponding to a network slice with which the user equipment wants to register,
• receive a first registration accept message as a response to the first registration request message from the AMF,
• wherein the first registration accept message comprises allowed NSSAI comprising at least one S-NSSAI allowed by the AMF, and
• request an update of a network slice selection policy (NSSP) associated with new S-NSSAI from the AMF when the new S-NSSAI not included in the requested NSSAI is included in the allowed NSSAI and the NSSP associated with the new S-NSSAI is not present,
• wherein the AMF is a network node for transmitting a policy update request message for the update of the NSSP to a policy control function (PCF) in response to a request from the user equipment, and
• wherein the PCF is a network node for delivering a policy update message comprising NSSP update information about the new S-NSSAI to the AMF in response to a request from the AMF.