The present disclosure relates to a communication technique for merging IoT technology with 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 homes, smart buildings, smart cities, smart cars or connected cars, healthcare, digital education, retail businesses, security- and safety-related services, and the like) on the basis of 5G communication technology and IoT-related technology. Embodiments of the present disclosure relate to a wireless communication system and, more particularly, to a cell activation method and device in a wireless communication system.