The magneto-optical rotation (MOR) of amorphous rare earth-iron thin films with reflecting layers and the characteristics of magneto-optical disc exerciser are described. The MOR of GdTbFe thin films increased from 0.27° to 0.5° by the addition of Cu reflector , and to 0.65° by supplementing an SiO2 intermediate film upon the Cu reflector. Furthermore in the case of a quadri-layer structure, which consisted of SiO, GdTbDyFe, SiO2 and Cu layers, the angle of rotation was augmented to 1.75°. The Magneto-optical disc player, making use of the above quadri-layer structure disc, attained a carrier-to-noise ratio (CNR) of 40 dB at 2 MHz, thereby proving the applicability of the equipment to digital file memory systems.