Etching method and residue removal method

An etching method of etching a silica-based residue containing a base component formed in an SiO2 film, includes selectively etching the silica-based residue by supplying an HF gas, an H2O gas or an alcohol gas to a target substrate having the SiO2 film, on which the silica-based residue is formed, and removing an etching residue caused by the selectively etching the silica-based residue, after the selectively etching the silica-based residue. The removing an etching residue includes a first process of supplying an H2O gas or an alcohol gas to the target substrate and a second process of heating the target substrate after the first process.