A device and method for transmitting a frame in a wireless LAN, with the method including the steps of: transmitting, by an AP, an RTS frame for medium protection to a first STA set; receiving, by the AP, CTS frames, in sequence, from each of a plurality of STAs included in a second STA set in response to the RTS frame, the second STA set being included in the first STA set; and transmitting, by the AP, each of a plurality of PPDUs to each of the plurality of STAs via each of a plurality of subbands for each of the plurality of STAs on an overlapping time resource.