Abstract: An etching method is capable of etching titanium selectively in the presence of copper. An etching liquid used in the method is low in toxicity and excellent in storage stability. The etching liquid includes at least one acid, such as, sulfuric acid, hydrochloric acid, or trichloroacetic acid, and at least one organic sulfur compound, such as a thioketone compound or a thioether compound.

Abstract: An object of the present invention is to provide: an etching liquid which is capable of etching titanium selectively in the presence of copper, and is further low in toxicity and excellent in storage stability; and an etching method using this etching liquid. The etching liquid of the present invention which is a liquid includes at least one acid selected from the group consisting of sulfuric acid, hydrochloric acid, and trichloroacetic acid, and at least one organic sulfur compound selected from the group consisting of a thioketone compound and a thioether compound, and makes it possible to etch titanium selectively in the presence of copper.