PURPOSE: To obtain a medium on which a high-density high reproduction output is recorded vertically by specifying the saturation magnetization of a vertical magnetization recording layer and a high-conductivity layer under it, and the thickness, etc., of the high-conductivity layer and a unipolar head under specific conditions.

CONSTITUTION: With regard to a solid disk on which vertical magnetic recording is performed by energizing a unipolar head 3 which has thickness Tr in the run direction of the medium, the saturated magnetization Ms(R) of a vertical magnetization recording layer 1 is so specified that Ms(R)>HK/4π(HK: anisotropic magnetic field). Further, the saturation magnetization Ms(HPL) of a high-conductivity layer 2 as the base of the recording layer 1 is so specified that Ms(HPL)≥ Ms(R), and the thickness δ(HPL) of the high-conductivity layer 2 is so specified that δ(HPL)>TR. For example, on a permalloy plate (having 0.1mm thickness) 2 having Ms nearly equal to that of Co, Co is vacuum-deposited 1 (to 0.25μm thickness) including several 0/0 P to form a two-layered medium. Then, the unipolar head 3 obtained by winding a coil around a permalloy plate having 0.1mm thickness TR is used to perform vertical recording.