A method of relaying data in a wireless communication system is provided. The method comprises: receiving data, transmitted over a first subframe from a base station, over a second subframe; and relaying the data to a user equipment over a third subframe which is placed after one or more subframes from the second subframe, wherein at least any one of the first and the second subframes is a non-detection subframe to which the user equipment does not attempt data detection. According to the present invention, the wireless communication system enables efficient data transmission between a base station and a relay station as compared to conventional subframe-configurated systems. Furthermore, the wireless communication system enables data transmission with improved wireless resource allocation efficiency.