Provided is a data transmission method using physical network coding in a relay station. The method may include an operation of receiving a first signal and a second signal from first and the second nodes, respectively, an operation of generating a third signal to which a physical network coding is applied based on the first signal and the second signal, an operation of forming a beam which maximizes a lower effective power between effective power of the first channel between the relay station and the first node and effective power of the second channel between the relay station and the second node, and an operation of transmitting the third signal to the first node and the second node based on the beam.