A new type of MAMMOS(Magnetic AMplifying Magneto-Optical System)was proposed. This method needs only a DC magnetic field for expanding and erasing the magnetic domains and RE(Rare-Earth)-rich GdFeCo was used for readout layer. In this system, 43dB of CNR was obtained for 0.25μm packed domains by applying 10kA/m of DC magnetic field. Compared with the conventional CAD(Center Aperture Detection)disk, CNR for the domains smaller than 0.4μm was improved. This method exhibited a high readout resolution in spite of an AC field-free method.