Provided are a method and device for efficient public land mobile network (PLMN) selection upon authentication failure for each network slice in a roaming network. A user equipment (UE) receives a registration rejection message from an access and mobility management function (AMF) of a first PLMN. The registration rejection message includes rejected network slice selection assistance information (NSSAI) including first single NSSAI (S-NSSAI) and cause value #62 for the rejected NSSAI. The UE: generates second requested NSSAI including second S-NSSAI on the basis that i) the UE does not have allowed NSSAI and configured NSSAI, and ii) default configured NSSAI includes the second S-NSSAI that is not included in the rejected NSSAI and corresponds to a network slice of which the UE requests registration; and transmits a second registration request message including the second requested NSSAI to the AMF of the first PLMN.