A method for transmitting wireless data using a piggyback technique includes the steps of: a) transmitting a predetermined request packet from a first communication unit to a second communication unit in a predetermined wireless network system; b) determining, by the second communication unit having received the request packet, whether to sequentially transmit an acknowledgement (ACK) packet indicating an acknowledged or unacknowledged state of the request packet and a data packet responding to the request packet to the first communication unit; and c) if it is determined that the ACK packet and the data packet should be sequentially transmitted, including, by the second communication unit, ACK information in a header of the data packet without transmitting the ACK packet to the first communication unit, and transmitting the data packet including the header equipped with the ACK information to the first communication unit.