Magnetic disk device that corrects position of head by demodulation

A magnetic disk device comprising:

• a disk including a zone servo boundary area including a first area of a first servo frequency, a second area of a second servo frequency, and a third area of the first servo frequency, in a servo area;
• a head including a write head for writing data to the disk and a read head for reading data from the disk;
• and
• a controller demodulating first servo data of the first area read by the head to derive a position of the head, and demodulating first corrected data of the third area read by the head to correct the position of the head, to position the head in association with a predetermined track,
• the first area, the second area, and the third area being aligned in order in a traveling direction of the head for the disk,
• the first area and the second area being adjacent to each other in a circumferential direction of the disk,
• the second area and the third area being adjacent to each other in the circumferential direction of the disk.