PURPOSE: An apparatus for processing a substrate is provided to prevent a radiation light and a reflection light from being projected to the center of a chamber by installing a shielding unit in the center of a lower part of the chamber. CONSTITUTION: A chamber offers a reaction space. A substrate mounting plate is located in the reaction space and substrate is placed therein. A heating unit(128) comprises a lamp(128a) arranged in the around the center hole and is located in the lower part of the chamber to heat the substrate mounting. A shielding unit prevents a projected light from being provided to the center hole.
