The present invention relates to a wireless communication system. More particularly, a method and a device for restricted access window-based channel access in a WLAN system are disclosed. The method whereby a station (STA) performs channel access in a wireless communication system according to one embodiment of the present invention may comprise the steps of: receiving restricted access window (RAW) cross-border transmission allowance (CBTA) information from an access point (AP) in case an RAW is allocated to the STA; and performing transmission by the STA on the basis of the RAW CBTA information. In case the RAW CBTA information is configured as a first value, transmission by the STA beyond the border of the RAW may be allowed.