A method and apparatus for transmitting channel status information (CSI) to a macro eNB (MeNB) by a relay node (RN) in a wireless communication system to which carrier aggregation is applied are disclosed. The method includes receiving a CSI reporting request corresponding to a specific secondary component carrier (CC) from the transmitter through a primary CC, establishing a reference resource for the CSI in association with one or more secondary CCs indicated by the CSI reporting request, and transmitting CSIs of the one or more secondary CCs to the transmitter through the specific secondary CC, using the established reference resource. The reference resource is set to the nearest subframe serving as a valid downlink subframe from a reception time point of the CSI reporting request.