Proposed are a method and apparatus for receiving a PPDU in a wireless LAN system. In detail, a reception STA receives a PPDU from a transmission STA through a first band and decodes the PPDU. The PPDU includes a preamble and a data field. The first band includes first and second subblocks. The data field includes first data for the first subblock and second data for the second subblock. The first data is generated on the basis of data in which constellation mapping is performed on encoded data bits. The second data is generated on the basis of data obtaining by duplicating the first data and applying phase rotation thereto.