PURPOSE: To improve both positioning and centering accuracy in a disk thickness direction to improve reliability and at the same time to simplify the structure of a disk driver, by forming a spindle and a disk holding part from a single material into a monolithic part.

CONSTITUTION: This disk driver consists of a spindle 1, a disk holding part 2, a permanent magnet 3 attached to the inner side of a top face of the part 2, etc. In this case, the spindle 1 and the part 2 are produced by the same material into a monolithic parts. Owing to this monolithic structure, the height of the part 2 that decides the head touch accuracy and the oscillation of the outer circumferential face of the part 2 which causes off-tracks can be minimized since both the outer circumference of the spindle 1 and the part 2 are processed at a time. As a result, the positioning accuracy of a disk driver can be improved.