The present invention provides a method for transmitting or receiving data in a wireless communication system, and an apparatus therefor. Specifically, a method for receiving data by a user equipment (UE) in a wireless communication system may comprise the steps of: receiving control information related to a first codeword and a second codeword; and on the basis of the control information, receiving the first codeword and the second codeword via a physical layer, wherein it is recognized on the basis of a pre-defined rule that the first codeword and the second codeword correspond to the same transport block within a higher layer of the physical layer.