PURPOSE: To eliminate an external magnetic field and to avoid an evil effect of said magnetic field, by using a ferrodielectric thin film to unify the electrode part and applying a DC electric field to said thin film to record the desired bit.

CONSTITUTION: A lower electrode 12 is provided on an insulated base part 11, and then the electrode 12 is unified with the part 11. A ferrodielectric thin film 13 is formed on the electrode 12, and a transparent electrode 14 is provided on the surface of the film 13. A DC electric field is applied to the upper and lower electrodes 15 and 16 of a disk player through an area between the electrodes 12 and 14, when the disk is attached to the player. With application of the electric field, the film 13 has an orientation of the natural polarization. As a result, the bit corresponding to an input signal can be recorded. The reproduction is carried out by detecting a turn of the deflecting face which is due to an electro-optical effect by means of a deflector and a light detector.