A method for transmitting and receiving a wireless signal in a wireless communication system and an apparatus therefor are disclosed. Specifically, a method for transmitting and receiving a wireless signal in an unlicensed band includes the steps of: performing a clear channel assessment (CCA) during a predetermined time interval in the unlicensed band; and transmitting a wireless signal in the unlicensed band when it is determined that the unlicensed band is in an idle state where the unlicensed band is not occupied by other wireless communication devices, wherein when the wireless communication device uses a directional antenna, a first difference between a CCA range and an interference range when the wireless signal is transmitted and received using the directional antenna may be adjusted to be equal to a second difference between the CCA range and the interference range when the wireless signal is transmitted and received using an omni-directional antenna.