A polishing liquid composition for a silicon oxide film according to the present invention includes cerium oxide particles, a water-soluble macromolecular compound, and an aqueous medium, and the water-soluble macromolecular compound is a water-soluble macromolecular compound including a betaine structure, excluding carbobetaine homopolymers and sulfobetaine homopolymers. The water-soluble macromolecular compound is preferably a water-soluble macromolecular compound containing a constitutional unit A including a betaine structure, and a constitutional unit B that is a constitutional unit other than the constitutional unit A and contains at least one group of a primary amino group, a secondary amino group, a tertiary amino group, a quaternary ammonium group, and salts thereof.