Disclosed is a method for generating a data block to be transmitted from a specific layer in a transmitting side to a receiving side in a wireless communication system. The method includes receiving an upper layer datei block from an upper layer and generating a lower layer data block including at least part of the upper layer data block and state indication information indicating a state of the upper layer data block, the state indication information being selected variably according to a logical channel through which the upper layer data block is received. This method optimizes overhead of a header of each upper layer data block according to contents of the upper layer data block and event situations associated with the upper layer data block, thereby increasing system efficiency.