A spindle motor includes a base, a rotor, a rotating shaft, a first turntable, and a second turntable. The rotating shaft is rotatably disposed on the base. The rotor having a top surface is disposed on the rotating shaft, part of which projects from the top surface of the rotor. The first turntable is disposed on the rotating shaft. The second turntable having a disk mounting surface is adjustably disposed over the first turntable, and is arranged to be rotated with the first turntable synchronously.