The present invention relates to a communication system and method for merging, with IoT technology, a 5G communication system for supporting a data transmission rate higher than that of a 4G system. The present invention provides a system and method by which a user equipment (UE) transmits, to an access and mobility management function (AMF), a first message including information related to a network slice in a first authentication, and receives, from the AMF, a third message including a result of a second authentication, wherein whether to require the second authentication is determined by the AMF based on the information and subscription information, and wherein the second authentication between the UE and a server is triggered based on the determination.