A method for steering traffic performed by a terminal in a wireless communication system and a terminal using the method are provided. The method is characterized by: receiving first system information including a PLMN-ID list on which identities (ID) of a public land mobile network (PLMN) are listed according to a specific order; receiving second system information including RAN auxiliary information related to steering traffic between a first network and a second network; and steering traffic between the first and the second networks based on the first and second system information, wherein the second system information provides RAN auxiliary information for each PLMN, includes the same number of pieces of RAN auxiliary information as the number of PLMNs on the PLMN-ID list, and includes the RAN auxiliary information in the same order as the specific order of the PLMNs on the PLMN-ID list.