Provided are a metal-polishing liquid that comprises an oxidizing agent, an oxidized-metal etchant, a protective film-forming agent, a dissolution promoter for the protective film-forming agent, and water; a method for producing it; and a polishing method of using it. Also provided are materials for the metal-polishing liquid, which include an oxidized-metal etchant, a protective film-forming agent, and a dissolution promoter for the protective film-forming agent.