A glass material of a glass spacer has a surface resistivity of 10.sup.3 to 10.sup.9 (Ω/sq) at 22 (° C.). The surface resistivity of a surface of the glass material of the glass spacer at 22 (° C.) is lower than the surface resistivity of an inner portion of the glass material at 22 (° C.). The glass spacer contains at least one oxide selected from the group consisting of TiO.sub.2, Nb.sub.2O.sub.5, WO.sub.3, and Bi.sub.2O.sub.3, as a glass component.

A glass material of a glass spacer has a surface resistivity of 10.sup.3 to 10.sup.9 (Ω/sq) at 22 (° C.). The surface resistivity of a surface of the glass material of the glass spacer at 22 (° C.) is lower than the surface resistivity of an inner portion of the glass material at 22 (° C.). The glass spacer contains at least one oxide selected from the group consisting of TiO.sub.2, Nb.sub.2O.sub.5, WO.sub.3, and Bi.sub.2O.sub.3, as a glass component.

A ring-shaped spacer is to be arranged in contact with a magnetic disk in a hard disk drive apparatus. A maximum height surface roughness Rz of an outer circumferential edge surface of the spacer is at least 1.5 m, and the spacer is made of amorphous glass.

A ring-shaped spacer is to be arranged in contact with a magnetic disk in a hard disk drive apparatus. A maximum height surface roughness Rz of an outer circumferential edge surface of the spacer is at least 1.5 m, and the spacer is made of amorphous glass.

A hard disk drive is a 3.5-inch hard disk drive on which a magnetic disk formed of an aluminum alloy substrate is mounted. A thickness Td of each of magnetic disks that are arranged in a stacked manner is 0.3 mm or more and 0.6 mm or less, the number N of the magnetic disks is 10 or more and 16 or less, and an outer diameter 2Rso of a spacer that is arranged between the magnetic disks is 35 mm or more and 65 mm or less. The outer diameter 2Rso (mm) of the spacer satisfies 2Rso60Td+70 and 2Rso0.5N.sup.2+16.5N73.

A hard disk drive is a 3.5-inch hard disk drive on which a magnetic disk formed of an aluminum alloy substrate is mounted. A thickness Td of each of magnetic disks that are arranged in a stacked manner is 0.3 mm or more and 0.6 mm or less, the number N of the magnetic disks is 10 or more and 16 or less, and an outer diameter 2Rso of a spacer that is arranged between the magnetic disks is 35 mm or more and 65 mm or less. The outer diameter 2Rso (mm) of the spacer satisfies 2Rso60Td+70 and 2Rso0.5N.sup.2+16.5N73.

When removing magnetic disks and spacers from a hard disk drive apparatus, as necessary, during the assembly of the hard disk drive apparatus, in order to suppress the occurrence of removal failures when removing the spacers using a gripping jig, a surface roughness Rz of an outer circumferential edge surface of a spacer is set to be at least 1.5 m.

When removing magnetic disks and spacers from a hard disk drive apparatus, as necessary, during the assembly of the hard disk drive apparatus, in order to suppress the occurrence of removal failures when removing the spacers using a gripping jig, a surface roughness Rz of an outer circumferential edge surface of a spacer is set to be at least 1.5 m.

In order to suppress the occurrence of adhesion between magnetic disks and spacers when the magnetic disks and the spacers are removed from a hard disk drive apparatus in which the magnetic disks and the spacers are installed, a surface roughness Ra of a main surface of a ring-shaped glass spacer to be arranged in contact with a magnetic disk is set to be not larger than 1.0 m, and an average inclination Ra of the main surface is set to be at least 0.02.

In order to suppress the occurrence of adhesion between magnetic disks and spacers when the magnetic disks and the spacers are removed from a hard disk drive apparatus in which the magnetic disks and the spacers are installed, a surface roughness Ra of a main surface of a ring-shaped glass spacer to be arranged in contact with a magnetic disk is set to be not larger than 1.0 m, and an average inclination Ra of the main surface is set to be at least 0.02.