The present invention relates to a method and apparatus for receiving available channel information in a wireless LAN system. According to one aspect of the present invention, in a method in which a first station (STA) receives available channel information in a wireless LAN system, wherein the first station operates as an unlicensed device that is allowed to operate in an available channel not used by a licensed device in a white space band, the first station receives, from a second station, a frame including an operating class field, a channel number field and a maximum transmission power field, and operates in the channel indicated by the operating class field and the channel number field, wherein said operating class field and said channel number field indicate the available channel which can be used by the unlicensed device, and said maximum transmission power field indicates the maximum transmission power permitted in the available channel.