A method for transmitting an uplink includes: an STA1 transmitting to an AP each of multiple RTS frames through at least one channel from among multiple first channels; the STA1 receiving from the AP at least one CTS frame through at least one channel from among the multiple channels which have received the RTS frames; and an STA2 receiving from the AP at least one CTS frame through at least one channel from among multiple second channels, wherein the at least one CTS frame includes STA identifier information and channel information, the STA identifier information includes information for indicating the STA1 and the STA2, and wherein the channel information includes information on an uplink channel1 allocated for transmitting a data frame1 of the STA1 and information on an uplink channel2 allocated for transmitting a data frame2 of the STA2.