A method for receiving, by a station (STA), a signal in a wireless LAN system comprises: a step of receiving a frame which includes a SIG-A field including MCS information for a SIG-B field, and the SIG-B field encoded on the basis of any one MCS set among from multiple MCS sets; and a step of decoding the SIG-B field on the basis of the MCS information included in the SIG-A field, wherein a specific value in the MCS information indicating a first MCS level of a first MCS set from among the multiple MCS sets is re-used to indicate a second MCS level of a second MCS set, and which MCS level of the first MCS level and the second MCS level indicated by the specific value is set in the SIG-B field is implicitly indicated by a status of a channel on which the frame is received.