The present invention provides a method and apparatus for performing contention-based uplink transmission in a wireless communication system. A terminal transmits a contention-based uplink signal to a base station. The base station detects a contention-based uplink signal that is transmitted from at least one terminal, and determines whether there exists a terminal corresponding to the detected contention-based uplink signal. The terminal receives an uplink (UL) grant from the base station. The terminal switches from a dormant station into an active state, based on the uplink grant. Here, the dormant state is a state where radio resource control connection is formed between the base station and the terminal but data is not actually transmitted, and the active state is a state where data transmission is actually performed.