A first polishing composition is used in chemical mechanical polishing for removing one part of the portion of a conductive layer positioned outside a trench. A second polishing composition is used in chemical mechanical polishing for removing the remaining part of the portion of a conductive layer positioned outside the trench and the portion of a barrier layer positioned outside the trench. The first polishing composition contains a specific surfactant, a silicon oxide, a carboxylic acid, an anticorrosive, an oxidizing agent, and water. The second polishing composition contains colloidal silica, an acid, an anticorrosive, and a completely saponified polyvinyl alcohol.