PURPOSE: To form a thin film magnetic disk with a high S/N ratio by impressing a DC magnetic field caused by a permanent magnet in the radius direction of a disk-like substrate and forming a magnetic film through a slit thereon.

CONSTITUTION: The bottom of a vacuum tank 7 is provided with an evaporating source 6 which is made of Co-Ni-P which Co as a main ingredient. The drive force of a motor 1 placed in the center of the upper part of the tank 7 rotates the substrate 3 through a conductive shaft. A slit is provided right under the motor 1, and permanent magnets 8 and 8' are installed in the magnets symmetric with a rotary shaft as a center. The center of the substrate 3 is mechanically punched out to remove it, and the turbulence in the magnetic direction is prevented. Moreover the slit 9 is provided with a shutter 4. Thus the shutter is attached and detached through the slit having the long side in the radius direction on the substrate 3, and a DC magnetic field is impressed in the direc tion vertical against the radius, whereby the magnetization facilitating shaft of the magnetic film can be always pointed in the circular direction. Accordingly the magnetization inversion is facilitated at recording and reproducing to improve the S/N ratio.