To provide a composition for surface treatment capable of treating a surface of a polished object to be polished having both of a silicon-silicon bond and a nitrogen-silicon bond by sufficiently removing defects on the surface of the polished object to be polished. The composition for surface treatment contains a nonionic water-soluble polymer (A) having a main chain including only a carbon atom or a main chain consisting of a carbon atom and a nitrogen atom, and an anionic water-soluble polymer (B) having a main chain including only a carbon atom and a side chain having a sulfonic acid group or a group having a salt thereof or a carboxyl group or a group having a salt thereof, and being bonded to the main chain including only a carbon atom, and the composition is used for surface treatment of a polished object to be polished containing a silicon-silicon bond and a nitrogen-silicon bond and a pH of the composition is less than 9.0.