Disclosed is an ultra-wideband (UWB) system and, more particularly, a UWB system using UWB ranging factor definition. The UWB system using the UWB ranging factor definition includes a memory in which a UWB ranging factor definition program is embedded and a processor which executes the program, wherein the program predefines UWB ranging factors to define a scrambled timestamp sequence (STS) index, an encryption key, and a nonce.