Disclosed are: a communication technique for merging, with IoT technology, a 5G communication system for supporting a data transmission rate higher than that of a 4G system; and a system therefor. The present disclosure can be applied to intelligent services (for example, smart home, smart building, smart city, smart car or connected car, healthcare, digital education, retail, security, and safety-related services, and the like) on the basis of 5G communication technology and IoT-related technology. Disclosed are a method and a device for supporting the connection of a terminal operating in an RRC inactivation mode.