To provide a polishing composition suitable for the use of polishing a polishing object having a film containing a silicon material having a silicon-silicon bond formed on a pattern containing an insulating film by a CMP method to form circuit patterns containing the silicon material and capable of also suppressing a remarkable reduction in polishing removal rate.
A polishing composition of this invention contains abrasives, a first water-soluble polymer containing a polymer compound containing a lactam ring and having a weight average molecular weight of less than 300,000, a second water-soluble polymer containing a polymer compound containing a lactam ring and having a weight average molecular weight smaller than that of the first water-soluble polymer, a basic compound, and water.