Abstract: A method for etching compound solid state material by a meltback method that provides fast etching speed and a smooth surface, and in which the problem of fast saturation of the solvent is solved, high workability is achieved, and the range of application targets is wide. Etching is performed at a desired location on the surface of the compound solid state material. A solvent for the material is placed in contact with a part of the surface of the material, and at least one part of the other surface of the solvent is placed in contact with the atmosphere, such that at least one volatile component of the structural component of the material that dissolves in the solvent easily evaporates.