Provided is a method for processing traffic by a terminal in a wireless communication system supporting a multiple access network. The method comprises receiving from a first access network traffic routing information, and processing traffic on the first access network based on the traffic routing information. The traffic routing information indicates whether at least one unit of traffic on the first access network can be processed through a second access network. Processing the traffic based on the traffic routing information involves determining whether the traffic can be processed through the second access network, and processing the traffic through the second access network when the traffic can be processed through the second access network.