Disclosed is a substrate treating apparatus. The substrate treating apparatus includes a process chamber having a treatment space in the interior thereof, a support unit configured to support a substrate in the treatment space, a gas supply unit configured to supply a treatment gas into the treatment space, and a plasma generating unit configured to generate plasma from the gas in the treatment space, wherein the plasma generating unit includes a high-frequency power source, a high-frequency antenna, to which a current is applied from the high-frequency power source, and an additional antenna provided to be spaced apart from the high-frequency antenna and to which a coupling current is applied from the high-frequency antenna.