The invention relates to a data transfer method in a multi-hop relay system. The data transfer method comprises: a step for allowing a base station to receive from a first terminal the channel information (Hd,1) between the base station and the first mobile station, a step for making the base station generate an interference cancellation precoding matrix using Hd,1, a step for forcing the base station to transfer first data to a relay station, and a step for making the relay station transfer the first data to the first mobile station and forcing the base station to transfer second data to a second mobile station, wherein the second data is converted using the interference cancellation precoding matrix. According to the disclosed data transfer method in the multi-hope relay system, the base station transfers data to another mobile station efficiently when the relay station transfers data to a mobile station. Therefore, the data transfer method is able to efficiently use the resources wasted in an existing data transfer method and improve the total data transmission rate of the base station.