Glass substrate for magnetic recording medium, magnetic recording medium, and method of manufacturing the same

A glass substrate which is for use in a magnetic recording medium and which has surface roughness Ra and Rmax, where Ra is representative of a center-line mean roughness, Rmax is defined as a maximum height representative of a difference between a highest point and a lowest point wherein:

• a surface roughness of at least a principal surface of the glass substrate is measured by the use of the interatomic force microscope (AFM),
• Ra falls within the range between 0.2 and 2.5 nm,
• Rmax falls within the range between 3 and 25 nm, and
• Rmax/Ra falls within the range between 3 and 35;
• and
• wherein:
• a surface parallel to a virtual principal surface is defined as a contour surface when it is assumed that the principal surface of said glass substrate is completely flattened,
• when roughness formed on the principal surface are cut by the use of the contour surface, a percentage rate of a total area of the principal surface for sum of areas of the cut cross sectional surface is defined as a bearing ratio,
• the contour surface having the bearing ratio of 50% is defined as a referential surface,
• each distance from the referential surface to each contour surface having each bearing ratio is specified as a bearing height,
• the bearing height of the contour surface having the bearing ratio of 2.5% is defined as B.H. (2.5) while the bearing height of the contour surface having the bearing ratio of 5.0% is defined as B.H. (5.0), and
• B.H. (2.5)/Rmax falls within the range between 0.1 and 0.5 or B.H. (5.0)/Rmax falls within the range between 0.1 and 0.45.