The present invention discloses a method for a base station to transmit a radio link monitoring-reference signal (RLM-RS) in an unlicensed band. In particular, the method may divide a frequency band for the RLM-RS into a plurality of sub-bands, perform a channel clearance assessment (CCA) for each of the plurality of sub-bands, and transmit the RLM-RS via each of the plurality of sub-bands on the basis of the result of performing the CCA.