The present document relates to a wireless communication system and, more specifically, to a method for flexibly supporting resource allocation in a wireless LAN system, and a method and an apparatus for signal transmission using the same. To this end, a first STA configures a radio frame comprising: a signaling (SIG) field including control information; and a data field in which data can be transmitted via a discontinuous channel or a channel having a bandwidth size that is supported by a legacy system. When the first STA transmits the configured radio frame to a second STA, the SIG field preferably comprises: information about a full bandwidth in which data can be transmitted via the data field; and null indicator information indicating a channel region of the full bandwidth that is not used in data transmission, or used channel indicator information indicating a channel region of the full bandwidth that is used in data transmission.