Method of avoiding medium defects in record/reproduce apparatus

In a record/reproduce apparatus, medium defects in magnetic disks are avoided without considerably losing record areas. In a record or reproduce mode, the plurality of magnetic disks are accessed in parallel by a plurality of magnetic heads and a plurality of record circuits or reproduce circuits. Regarding the record areas where only one of the magnetic disks has the medium defect, a control circuit controls a head change-over circuit so that a record area in a spare magnetic disk may be accessed by a spare magnetic head instead of the defective record area. Besides, regarding the record areas where two or more of the magnetic disks have the medium defects, the control circuit operates so that spare record areas in the two or more magnetic disks may be accessed instead of the defective record areas.