According to an embodiment of the present specification, a method for transmitting an uplink frame in a wireless local area network (WLAN) system and performed by a user station (STA) includes: receiving from an access point (AP) a trigger frame comprising association identifier information for orthogonal frequency division multiple access (OFDMA)-based random access and allocation information indicating a resource unit, wherein the association identifier information indicates any one of a first value irrelevant to whether being associated with the AP, a second value for a first STA group associated with the AP, and a third value for a second STA group un-associated with the AP; and performing a countdown operation according to the association identifier information based on a backoff value which is set in a backoff counter of the user STA in order to transmit the uplink frame.