Disclosed herein is a spatial reuse (SR) method of a first station (STA) associated with a first basic service set (BSS) in a wireless LAN (WLAN) system may include receiving an inter-BSS physical protocol data unit (PPDU) from an AP or second STA associated with a second BSS different from the first BSS, wherein the inter-BSS PPDU includes a physical (PHY) preamble and an inter-BSS frame and the high efficiency (HE)-signal (SIG) A field of the PHY preamble includes an SR indicator indicating whether SR is allowed; performing CCA on a channel based on a clear channel assessment (CCA) level, that is, a criterion by which the busy or idle state of the channel is determined if the SR indicator indicates that the SR is allowed; and transmitting a signal through the idle channel when the channel is idle as a result of the execution of the CCA.