A spindle motor includes a stationary portion and a rotating portion including a rotor hub, and includes a recording disk and a clamper mounted thereon. The rotor hub includes a hub circular plate portion whose outer circumferential portion includes a hub slanting surface, and a hub cylindrical portion whose outer circumferential portion includes a hub screw portion. The hub screw portion, to which the clamper is screwed, includes at least a first hub screw groove, a first hub screw thread arranged to be adjacent to the first hub screw groove, and upper and lower flanks arranged to together define the first hub screw thread. The hub slanting surface connects with the first hub screw groove. The length of the hub slanting surface is longer than the length of the upper flank.