To provide a setter for heat treatment of a glass substrate, which is hardly warped and deformed even if it is repeatedly used in the temperature range in which the glass substrate is heat treated; and to provide a method for manufacturing the same.

The setter for heat treatment of the glass substrate is formed from a plate-like inorganic heat-resistant material. The setter mounts the glass substrate on one surface thereof for heat treating the substrate and is characterized in that the concentration of K2O is 1-5 mass% at the position separated from the mounting surface for mounting the glass substrate toward inside by 5 m and is 0.8 mass% at the position separated from the mounting surface toward inside by 1 mm. The method for manufacturing the setter for heat treatment of the glass substrate is characterized by injecting K ion into one or both surfaces of the plate-like inorganic heat-resistant material or a precursor material thereof from a supply source at the outside.