Polishing composition, method for polishing substrate and method for producing substrate

Abstract

There is provided a polishing composition which is used for polishing a magnetic disk substrate and in which the amount of silica abrasive residues on an object to be polished is suppressed. The magnetic disk substrate polishing composition contains silica particles as abrasives, an acid, an oxidant and water. Here, in the polishing composition, a logarithm with base of an etching amount X [ng / h·mm2] of a soft steel plate measured in a soft steel etching test, in which the soft steel plate is immersed in the polishing composition, is 2.0 or more and 10 4.0 or less.