Abstract: A security method in a physical layer and a wireless communication system using the same are provided. A wireless communication Access Point (AP) whose security has been enhanced in the physical layer includes a storage unit that manages channel bandwidth pattern data, a controller for sequentially acquiring channel bandwidth data from the channel bandwidth pattern data, a PLL controller for changing a channel bandwidth based on the acquired channel bandwidth data, and a wireless interface unit for performing wireless communication with a wireless communication terminal using the changed channel bandwidth. The channel bandwidth pattern data is identical to channel bandwidth pattern data stored in the wireless communication terminal, and the wireless communication terminal and the wireless communication AP are synchronized with each other such that the wireless communication terminal and the wireless communication AP perform wireless communication using the same channel bandwidth.