Disk device

A disk device comprising:

• a case having a sheet-shaped base with an open upper surface formed of a soft magnetic material and a sheet-shaped top cover with an open upper surface formed of a soft magnetic material and attached to the base;
• a disk-shaped recording medium which includes a substrate, a soft magnetic backing layer formed on the substrate, and a magnetic recording layer formed by being overlapped on the soft magnetic backing layer and having perpendicular magnetic anisotropy, the recording medium being arranged in the case;
• and
• a mechanical unit including a head which carries out an information processing to the recording medium, a head actuator which supports the head, and a drive motor which supports and rotates the recording medium, the mechanical unit being arranged on the base,
• the base having a thickness of 0.5 mm or more and the top cover having a thickness of 0.25 mm or more, respectively, and
• the base and the top cover having a relative permeability of 700 or more and a saturation flux density of 1.4 (T) or more.