The spindle motor comprises a shaft, a rotor, and a medium-carrying surface. The rotor is disposed on the outer peripheral side of the shaft, and rotates about the shaft. The medium-carrying surface is disposed on the rotor, and carries a circular-disk-form recording medium. The recording medium is pressed and fastened to the medium-carrying surface by a clamping member. The clamping member is a member that presses the recording medium against a medium-carrying surface. The average value of the widths of the profile peaks in the mean line for the primary profile of the medium-carrying surface in the radial direction is smaller than the average value of the widths of the profile valleys.