Proposed are a method and an apparatus for transmitting data in a wireless LAN system. Particularly, an AP transmits a PPDU to one STA. The AP transmits data to the one STA over a first NCCB band or a second NCCB band on the basis of the PPDU. The PPDU includes a first signal field and a second signal field. The first NCCB band is a 40 MHz or 60 MHz band generated by bonding a discontinuous 20 MHz band in an 80 MHz band. The second NCCB band is an 80 MHz, 100 MHz, 120 MHz, or 140 MHz band generated by bonding a discontinuous 20 MHz band in a 160 MHz band. The first signal field includes first information and second information. The first information is NCCB indication information on whether or not an NCCB can be performed. The second information is NCCB bandwidth information for a band to be used for transmitting the PPDU from the first NCCB band and the second NCCB band.