A polishing composition for semiconductor wafer polishing comprising, colloidal silica prepared from an active silicic acid aqueous solution obtained by removal of alkali from alkali silicate and at least one nitrogen containing basic compound selected from a group consisting of ethylenediamine, diethylenediamine, imidazole, methylimidazole, piperidine, morpholine, arginine, and hydrazine, wherein pH of the colloidal silica is of 8.5 to 11.0 at 25° C. by containing quaternary ammonium hydroxide.