A substrate treating apparatus includes a substrate support unit with a chuck on which a substrate is loaded; a bottom chamber having an open top and configured to surround the circumference of the chuck; a top chamber configured to open or close the top of the bottom chamber such that the substrate is dried while the top chamber is sealed from the outside; and a direct injection nozzle member installed at the top chamber to inject fluid directly to the substrate while the top of the bottom chamber is closed. According to the substrate treating apparatus, drying efficiency of an entire substrate is enhanced, external contaminants are blocked, and generation of an oxide layer is suppressed.