Disclosed are a method for configuring a preamble for a communication system in order to effectively use a packet transmission bandwidth, a preambler, and an apparatus for generating a packet using the same. The preambler includes: a mode determining unit receiving frame characteristics information, extracting frame information to be transmitted through a preamble, and determining a transmission mode corresponding with the extracted information; and a code generation unit receiving the transmission mode information which has been determined by the mode determining unit and generating a preamble made up of a combination of sub-preamble code strings corresponding with the transmission mode.