The inventive concept provides a substrate treating apparatus. The substrate treating apparatus includes a housing having a treating space for treating a substrate; a support unit configured to support the substrate at the treating space; and a plasma source for generating a plasma from a process gas supplied into the treating space; an exhaust line connecting to the housing and exhausting an atmosphere of the treating space; and a pressure adjusting unit positioned between the support unit and the exhaust line and configured to adjust an exhaust pressure exhausted from the exhaust line, and wherein the pressure adjusting unit includes: an opening/closing member for opening and closing the exhaust line; a lifting/lowering member for moving the opening/closing member in an up/down direction; and an elastic member for providing a restoring force to the lifting/lowering member.