A polishing composition and a rinsing composition according to the present invention can effectively suppress wafer contamination caused by metal impurities. The polishing composition includes a chelating agent, an alkali compound, silicon dioxide and water. The rinsing composition includes a chelating agent, an alkali compound and water. The chelating agent contained in the polishing composition and the rinsing composition is an acid represented by the following chemical formula (1) or a salt thereof. In the chemical formula (1), each of Y.sup.2 and Y.sup.3 represents an alkylene group, n is an integer of 0 to 4, each of 4+n substituents represented by R.sup.8 to R.sup.12 is an alkyl group. At least four of the alkyl groups have a phosphonic acid group. ##STR00001##