PURPOSE: To improve the yield by preventing excessive adhesion of metallic foil in the outer peripheral part of a winding core occurring in expansion and shrinkage of a winding core and the metallic foil on the outer side of the winding core and wrinkles and partial repture by such adhesion at the time of an annealing treatment to soften the hard metallic foil coil.

CONSTITUTION: The metallic foil 1 having a thickness of 8 to 35μm is subjected to embossing of roughness of #30 to #70, depth of 0.3 to 0.8μm and pitch of 0.2 to 1.0mm to form the metallic foil having an adequate rugged surface. Two sheets of such metallic foil are superposed on each other and adhered to form a laminate 2. Such metallic foil laminate 2 is wound as a cushion on the winding core a several number of times, by which adequate cushion layers are formed on the outer side of the winding core. The cushion layers relieve the compression of the metallic foil near the winding core of both of the winding core and the metallic foil which arises at the time of the heat treatment by annealing of the metallic foil coil, thereby reducing the occurrence of the defective parts.