The present invention provides a substrate treating apparatus, including: a treatment container having a treatment space therein; a support unit for supporting and rotating the substrate in the treatment space; and a liquid supply unit for supplying a liquid onto the substrate, in which wherein the support unit includes: a body on which the substrate is seated; and a support shaft coupled to the body, and an upper surface of the body is provided with a central portion including a center of the body and an edge portion surrounding the central portion, and a vacuum hole is formed in the central portion, and a groove is formed in the edge portion.