A method and a device for transmitting a wake-up frame in a wireless LAN system are proposed. In particular, the transmission device configures a PPDU to which a first wireless LAN system is applied. The transmission device transmits, via the PPDU, a wake-up frame to which a second wireless LAN system is applied. The PPDU is transmitted via a first frequency band. The PPDU comprises a signal field and a data field. The signal field indicates that a data frame is transmitted in at least one RU excluding three 26-RUs located at the center of a second frequency band included in the first frequency band. The wake-up frame is transmitted via a 4 MHz band located at the center of the three 26-RUs. A coefficient is inserted in a first subcarrier constituting the 4 MHz band. The wake-up frame has an OOK scheme applied thereto and thus comprises an on signal and an off signal.