Provided is a method for transmitting a data unit in a wireless local area network system, according to one embodiment. The method comprises transmitting a signal field, transmitting a first data symbol for a first data field, and transmitting a second data symbol for a second data field. The signal field, the first data symbol, and the second data symbol are transmitted through a 1 MHz channel bandwidth having a band of 1 GHz or less. Two pilot tones are inserted to each of the first data symbol and the second data symbol.