A data transmission apparatus in a wireless communication system includes: a data field generation unit configured to generate a data field for transmitting data; a signal field generation unit configured to generate a signal field for transmitting information on the data field; and a transmission unit configured to transmit a data packet containing the data field and the signal field. The signal field includes a rate bit, a reservation bit, a length bit, a parity check bit, and a tail bit, and the data transmission apparatus transmits a check bit for checking whether the signal field is normal or not through two or more bits of the bits of the signal field.