PURPOSE: To eliminate the undesirable influence of a back coating layer and over coating layer on a magnetic layer and to prevent drop-out by forming the tin film type magnetic layer on a web, then taking up the web, applying and forming the back coating layer and over coating layer thereon, and coiling and cutting the web.

CONSTITUTION: While fins 11 are held heated to a desired temp., a ferromagnetic material 9 set in a crucible 8 for an evaporation source is heated and evaporated by, for example, an electron beam generator 7 and the vapor flow thereof is partly shut off by a mask 10 and is diagonally deposited by evaporation on the substrate 2 moving along a cylindrical can 5. After the thin film type magnetic layer 32 is formed on the substrate in such a manner, the web is once taken up and the back coating layer 31 is applied and formed on the surface opposite to the magnetic layer 32 and the over coating layer is coated and formed on the magnetic layer 32 in the ensuing stage. The web is then coiled and cut. The generation of staining by the fillers, etc., of the back coating layer 31 is thereby prevented and the drop-out of the signal is prevented.