The invention provides a glass substrate capable of being used in various devices and requiring a high level surface cleanness, especially provides a glass substrate used in an information recording medium which possesses various physical properties needed by a next-generation information recording medium taking a vertical magnetic recording mode as a representative. In order to deal with the high density, a magnetic head impact generated by a pollutant adhered to the substrate surface is restrained to make a recording regeneration performance good after the medium forms a film. In addition, the invention provides a substrate used in an information recording medium possessing a high damage toughness and a glass material processing the glass substrate with an excellent processability, the glass material may become a necessary HAMR in terms of dealing with the future increase in the recording density is high in heat resistance performance, and is suitable for a direct pressuring method of carrying out a thin plate processing on melt glass at a low cost. The glass substrate of the invention is characterized in that a surface Zeta electric potential value of the glass substrate is less than minus 50 mv, and is obtained by using a material containing Na<2> SO<4> as a buffer, and detecting a water solution of which the PH is adjusted to be 10 via H<2> SO<4> and N OH.