Abstract: A polishing liquid composition for a silicon wafer, wherein the composition comprises silica particles (component A), at least one kind of nitrogen-containing basic compound (component B) selected from an amine compound and an ammonium compound, and a water-soluble macromolecular compound (component C) that contains 10 wt % or more of a constitutional unit I represented by a general formula (1) below and has a weight average molecular weight of 50,000 or more and 1,500,000 or less; and the pH at 25° C. is 8.0 to 12.0. In the general formula (1), R1 and R2 each independently represents a hydrogen, a C1 to C8 alkyl group, or a C1 to C2 hydroxyalkyl group, and R1 and R2 are never both hydrogens.