A spindle motor including a rotatable hub is provided on a case, and a disk is fitted on an outer periphery of the hub. A disk damper is fixed to an end portion of the hub to hold the disk on the hub. The disk damper integrally includes a clamp portion fixed to the end portion of the hub to hold a centre portion of the disk, and a substantially annular straightening portion extending outwards from the clamp portion in a radial direction and facing to a surface of the disk with a predetermined gap.