Abstract: In an alignment disk for use in adjustment or inspection of a magnetic read/write head in a floppy disk drive unit, which further includes an erase head, the alignment disk is provided with first regions in which signals are prerecorded and second regions in which no signals are prerecorded, the first and the second regions being alternately disposed along a locus followed by the read/write head when the disk is rotated. The length of each of the first region is smaller than the distance between read/write head and the erase head and the length of each of the second regions are larger than the distance between the read/write head and the erase head.