According to one embodiment, a disk drive includes a detection signal producing module configured to produce a detection signal by reading each of the spiral servo patterns, the spiral servo patterns being read by a head while the head scans a circumferential direction region on the disk media. A position error computation module is configured to produce servo burst signals A, B, C, and D using a plurality of frames obtained by dividing the detection signal at even time intervals, at least one burst signal of the servo burst signals being produced using at least two frames in the frames, and to compute a position error of the head based on amplitude values of the produced burst signals.