Provided is a method of etching a silicon oxide film, which includes supplying a mixture gas of a halogen element-containing gas and a basicity gas onto a surface of the silicon oxide film; modifying the silicon oxide film to produce a reaction product; and heating the reaction product to remove the reaction product. Modifying the silicon oxide film and heating the reaction product are performed using one chamber. In heating the reaction product, the reaction product is selectively heated by a heating unit.