PURPOSE: To allow the easy and rapid recording, reproducing and erasing of information by freely attachably and detachably superposing optical head arms and disposing magneto-optical disk media in the spacings between the optical head arms of the respective layers.

CONSTITUTION: Two pieces of the ractilinear arms 1, 5 are intersected at a specified angle and are integrally formed. The optical head arms 9a to 9g having optical pickup means 3 and bias magnetic field impressing means are successively superposed along the central axis of the intersecting part A apart specified spacings and are stacked in the form of layers on the respective rectilinear arms 1 and 5 freely movably in the axial direction of the arms. The attachment and detachment of the magneto-optical disk media into and from the spacings between the optical head arms 9a to 9g of the respective layers are possible in this way and the recording, reproducing and erasing of the prescribed information on and from the desired magneto-optical disk medium are executed by irradiating the medium with a light beam.