Disk device and head stack assembly having damper on inclined surface of load beam

A head stack assembly comprising:

• an arm with a through hole configured to rotate around a rotation axis, and having:
• a first surface spaced from the rotation axis in a first direction orthogonal to the rotation axis, and
• a second surface opposite the first surface, the through hole being open to the first surface and the second surface;
• a base plate having:
• a third surface facing the first surface, and
• a first protrusion protruding from the third surface to fit in the through hole;
• a load beam attached to the base plate and extending from the base plate in a direction between the first direction and a direction which the first surface faces, and having:
• a fourth surface facing a direction between the direction which the first surface faces and a second direction opposite to the first direction, and
• a fifth surface opposite to the fourth surface and facing a direction between the first direction and a direction which the second surface faces;
• and
• a damper attached to the fifth surface, wherein
• a value obtained by dividing a first distance between the first surface and the second surface by a second distance between an end of the damper and an axis of the through hole is 0.11 or less, the end of the damper being in the second direction.