PURPOSE: To polish the work of copper or a copper alloy uniformly, readily in a short time by subjecting the work to barrel polishing, by using a chemical polishing agent of a liquid mixture of monocarboxylic acid and hydrogen peroxide or the mixture added further with nitric acid.

CONSTITUTION: A chemical polishing agent contg. 200W2g/l acetic acid as monocarboxylic acid and 150W1g/l hydrogen peroxide or contg. 200W1g/l formic acid and 250W2g/l hydrogen peroxide is suitable as a compd. for barrel polishing of the work of copper and a copper alloy. Further the speed of polishing can be increased by adding a small amt. of nitric acid. In the case of adding the nitric acid, it is adequate to contain the same at ≤1.2mol ratio between the nitric acid and the acetic acid to the hydrogen peroxide within a 0.7W1.0 range of molar ratio between the acetic acid and the hydrogen peroxide, or at ≤0.7mol ratio between the nitric acid and the formic acid to the hydrogen peroxide in a 0.3W0.5 range of molar ratio between the formic acid and the hydrogen perioxide.