In the base bracket of the motor, the bottom-inner surface of the base bracket includes a first bottom-inner area arranged over a circuit board attaching portion of a bottom-outer surface to which the circuit board is attached, and a second bottom-inner area arranged other than the first bottom-inner area in a level axially lower than the first bottom-inner area. The second bottom-inner area defines a base of the concave portion arranged in the bottom-inner surface of the base bracket. A characteristic frequency of the disk storage device using the motor with the base bracket is preferably adjustable by changing the depth or width of the concave portion while the strength of the base bracket is preferably maintained.