MANUFACTURING METHOD OF MAGNETIC DISK SUBSTRATE

PROBLEM TO BE SOLVED: To provide a manufacturing method of a magnetic disk substrate capable of decreasing scratches and projection defects after polishing process.SOLUTION: The manufacturing method of a magnetic disk substrate includes a step of polishing a polishing object substrate 3. The polishing process uses a holding member 1, for the polishing object substrate, which contains resin. The polishing object substrate holding member satisfies one of conditions (1) and (2) shown below. The condition (1) is that contents of Al, Mg, and Ti metal ions in the holding member 1 are respectively 10 ppm or less. The condition (2) is that a residual amount of ashing process of the holding member 1 is 0.10 mass% or less.