PURPOSE: To correct a positional deviation with certainty by isolating an address part and a data part provided in each sector at a predetermined interval in an apparatus using composite heads formed by isolating a recording head and a reproducing head.

CONSTITUTION: Tracks of a magnetic disk are divided into a plurality of sectors, and a gap part, a servo signal part 1, an ID part 2 and a data part 3 are written on each sector. A drawing signal, a cylinder number, a head number, a sector number, etc., of a variable frequency oscillator corresponding to art ID part (N) 2 of the N-th sector are recorded on the (N-M)-th sector (N-M). Thus, the parts 3 and 2 are isolated thereby to extend a time until data is recorded after the part 2 is detected, and correction of a positional deviation can be completed with certainty during this period.