PURPOSE: To obtain a device which is capable of performing magnetic field modulation/optical modulation overwrite, has high performance and is miniaturized by moving an electromagnet for optical modulation type recording magnetic bias, interlocking with the saving operation of a magnetic head for magnetic field modulation type recording bias.

CONSTITUTION: A disk cassette is loaded on a cassette holder 50 and it is detected by the detection mechanism on the side of a magneto-optical disk device is detected and the classification of a disk 1 is judged. When a disk for which a magnetic field modulation overwrite is possible is loaded, a plunger 20a is pulled in by driving a solenoid 20 and a floating type magnetic head 3 is loaded on the disk 1 by turning the retreating mechanism 16 of the head 3. At the same time, the plunger 20a turns a driving arm 23 via a repeater arm 24 and a sliding member 22 is made to slide. Therefore, the magnetic discharging part of the tip part of a core 40 does not hinder the head 3 even if it operates in a state that the head 3 approaches to the disk 1, is capable of retreating from the lower part of the head 3 and the disk 1 and is capable of performing high speed writing.