The present invention disclosed herein relates to a substrate treating apparatus, and more particularly, to an apparatus for treating a substrate using plasma. Embodiments of the present invention provide substrate treating apparatuses including a chamber having a treating space defined therein, a support member disposed in the chamber to support a substrate, a gas supply unit supplying a gas into the chamber, a plasma source generating plasma from the gas supplied into the chamber, a baffle disposed to surround the support member in the chamber and having through holes to exhaust a gas in the treating space, and a shielding unit preventing an electromagnetic field from an inside of the chamber to an outside of the chamber.