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 receiving from an access point (AP) setting information of a time window, which does not allow channel access of the STA in a traffic indication map (TIM) mode and which is repeatedly set in a cyclic manner; and carrying out the channel access on the basis of the time window, wherein the setting information includes starting point information of a specific time window and cycle information of the time window, wherein the time window is repeatedly set for every cycle that is indicated by the cycle information of the time window.