The present invention relates to a wireless communication system, and more specifically, disclosed are a method and an apparatus for accessing a channel in a WLAN system. A method for accessing the channel from a station (STA) in the wireless communication system, according to one embodiment of the present invention, comprises the steps of: receiving from an access point (AP) setting information with respect to at least one slot allowing channel access by the STA; and beginning the channel access from a slot boundary of the at least one slot, wherein the channel access may begin without a clear channel assessment (CCA).