A polishing composition contains a nitrogen-containing compound and abrasive grains, and the pH of the composition is in the range of 1 to 7. The nitrogen-containing compound in the polishing composition preferably has a structure expressed by a formula: R1—N(—R2)—R3 in which R1, R2, and R3 each represent an alkyl group with or without a characteristic group, two of R1 to R3 may form a part of a heterocycle, and two of R1 to R3 may be identical and form a part of a heterocycle with the remaining one. Alternatively, the nitrogen-containing compound is preferably selected from a group consisting of a carboxybetaine type ampholytic surfactant, a sulfobetaine type ampholytic surfactant, an imidazoline type ampholytic surfactant, and an amine oxide type ampholytic surfactant. A polishing composition may contain a water-soluble polymer and abrasive grains, and the pH of the composition is in the range of 1 to 8.