Disclosed in the present specification is a method by which a user equipment (UE) performs access control. The method can comprise the steps of: transmitting a protocol data unit (PDU) session establishment or modification request message; and receiving a PDU session establishment or modification rejection message. The rejection message can comprise information on a backoff timer and session network slice selection assistance information (S-NSSAI). The method can comprise the steps of: driving the backoff timer while being linked with the S-NSSAI; and performing access control on the basis of the S-NSSAI.