According to an embodiment of the present specification, a method for accessing a wireless medium in a wireless local area network (LAN) system includes: receiving, by a wireless device, from an access point (AP) a packet including identification information indicating a receiving device which solicits a response frame, wherein the identification information is information included in a physical layer (PHY) header of the packet, the packet includes a broadcast frame, and the broadcast frame includes duration information indicating a time for deferring the access to the wireless medium; and if the wireless device is not the receiving device indicated by the identification information, setting, by the wireless device, a network allocation vector (NAV) on the basis of the duration information.