A polishing composition includes silicon dioxide, an alkaline compound, an anionic surfactant, and water. The silicon dioxide is, for example, colloidal silica, fumed silica, or precipitated silica. The alkaline compound is, for example, potassium hydroxide, sodium hydroxide, ammonia, tetramethylammonium hydroxide, piperazine anhydride, or piperazine hexahydrate. The anionic surfactant is at least one selected from a sulfonic acid surfactant, a carboxylic acid surfactant, and a sulfuric acid ester surfactant. The polishing composition can be suitably used in applications for polishing a silicon wafer.