[Problem] To provide an etching method that can increase selectivity of the etching of material to be processed and a resist, a sapphire substrate processed by this etching method, and a light emitting element provided with this sapphire substrate. [Solution] This etching method uses a plasma etching device and includes: a resist film forming step that forms a resist film on material to be processed; a pattern forming process that forms a prescribed pattern in the resist film; a resist modification step that exposes the resist film in which the pattern has been formed to plasma under prescribed conditions for modification and increases the etching selectivity by modifying the resist film; and an etching step for the material to be processed that exposes the material to be processed to plasma at conditions for etching that differ from the modification conditions and carries out etching of the material to be processed with the resist for which the etching selectivity has been increased as a mask.
