Provided are a chemical-mechanical polishing composition and a chemical-mechanical polishing method capable of polishing a semiconductor substrate containing a conductive metal such as tungsten or cobalt flatly and at high speed as well as reducing surface defects after polishing. The composition for chemical-mechanical polishing contains (A) silica particles having a functional group represented by general formula (1) and (B) a silane compound. —COO-M+ . . . (1) (M+ represents a monovalent cation.)