An AP downlink multi-user transmission method in a wireless communication system, according to one embodiment of the present invention, comprises the steps of: generating a DL MU PPDU, wherein the DL MU PPDU comprises resource allocation information for uplink MU transmission by a station (STA); transmitting the DL MU PPDU to the STA; and, on the basis of the DL MU PPDU, receiving a UL MU PPDU generated by the STA, wherein the UL MU PPDU comprises a first part having a first IDFT/DFT cycle, and a second part having a second IDFT/DFT cycle that is four times the first IDFT/DFT cycle, wherein the first part may be received through at least one 20 MHz channel in a position corresponding to a frequency resource indicated by the resource allocation information, and the second part may be received by using the frequency resource indicated by the resource allocation information.