PURPOSE: To compactly record and to stably store an extremely large amount of information and also to rewrite these information any number of times by initializing or erasing a tape type recording medium by the external magnetic field of a permanent magnet or an electromagnet having no contact with the recording medium.

CONSTITUTION: A magneto-optical tape 1 is initialized or erased by an external magnetic field 3 which is generated in the direction orthogonal to the tape 1 by a permanent magnet (electromagnet) 2 placed at a position ahead of an optical head and having no contact with the tape 1. As the tape 1 has no revolving action unlike a magneto-optical disk, it is difficult to erase and record the information by the same optical head like a disk. Therefore, it is most rational to initialize or erase the tape 1 at a position ahead of the optical head against the tape running direction and by means of only a magnetic field. Furthermore it is desirable to impress the magnetic field to the entire width of the tape 1 for its initialization or erasion in reference to simplification of the device constitution. Then a permanent magnet is also preferable in regard of the power consumption.