Disclosed is a method by which a terminal reports channel status information to a base station in a wireless communication system. Particularly, the method comprises the steps for attempting to detect a reference signal repeatedly transmitted multiple times for each reference signal transmission unit; setting the reference signal transmission unit as an effective reference resource for the channel state information when the reference signal is detected in a preset section within the reference signal transmission unit; measuring the channel state information at the effective reference resource; and reporting the channel state information to the base station.