A substrate treating apparatus, including a process chamber having a bottom portion configured to secure a substrate while a substrate treating process is performed on the substrate; and a dielectric window arranged at an upper portion of the process chamber to define a process space, and including: an insulative body, an antenna disposed on an upper surface of the insulative body, a protection layer disposed on a lower surface of the insulative body, and an etch resistor protruding from at least a portion of the protection layer toward the process space, wherein, based on power being applied to the antenna, a plasma is generated in the process space, and wherein the insulative body is protected from the plasma by the protection layer and the etch resistor.