A magnetic-disk evaluation apparatus includes a magnetic head positioned relative to a magnetic disk including temporary servo signals. Fluctuation of a magnetic head in a seek direction is measured using a measurement device. A measuring rotating arm moves in tandem with a rotating stage holding a rotary positioner. The measurement device is on the measuring rotating arm. The rotary positioner is controlled on the basis of temporary servo signals to position the magnetic head on a circle, concentric from a center of a spindle motor. Fluctuation of the magnetic head in the seek direction is measured to detect the displacement of the magnetic head and to determine whether the temporary servo signals are acceptable based upon the displacement and an outside standard.