Disclosed are method and device for selecting a cell in a wireless communication system. In particular, a method for selecting a cell by a terminal in a wireless communication system comprises the steps of: transmitting a random access preamble in a cell, which is selected by a terminal, to a base station; receiving a random access response from the base station; and, as a response to the random access response, transmitting an uplink message to the base station through a physical uplink shared channel (PUSCH), wherein the uplink message can comprises a radio resource management (RRM) measurement value which has been measured on the basis of a reference signal.