A magneto-optical disk including a transparent substrate, pit strings containing information formed in spiral or concentric form on a surface of the transparent substrate, a magneto-optical recording medium layer for covering the surface of the transparent substrate having the pit strings formed thereon, and magneto-optical recording areas formed by spiral or concentric flat portions between adjacent pit strings. An optical pickup for reproducing pit information and magneto-optically-recorded information from the magneto-optical disk. A magneto-optical disk drive for recording and reproducing information on the magneto-optical disk. The magneto-optical disk has a memory capacity which is twice the memory capacity of a conventional magneto-optical disk having ROM, and is accessed at high speeds.