A method and apparatus for transmitting a PPDU on the basis of S-TDMA in a wireless LAN system are presented. In particular, an AP generates a PPDU, and transmits the PPDU to a first STA and a second STA. When a PPDU further comprises a third signal field, the third signal field comprises information about S-TDMA. The information about S-TDMA comprises STDMA indication information indicating that S-TDMA can be carried out, first symbol offset information about a first data field, and second symbol offset information about a second data field. The S-TDMA indication information comprises information indicating that the first and second data fields are assigned to a first RU. The first data field is transmitted from the first RU during a first symbol determined on the basis of the first symbol offset information. The second data field is transmitted from the first RU during a second symbol determined on the basis of the second symbol offset information.