An apparatus for treating a substrate includes a housing having a treatment space inside, a gas supply unit that supplies a hydrophobic gas into the treatment space to hydrophobicize the substrate, and a support unit that supports the substrate in the treatment space. The support unit includes a support plate, a heating member that heats the substrate placed on the support plate, and a height adjustment member that changes a position of the substrate between a first position spaced apart upward from an upper surface of the support plate by a first distance and a second position spaced apart upward from the upper surface of the support plate by a second distance, and the second position is a higher position than the first position.