The present invention magnetic material such as cobalt component to provide a hard disk for flattening film forming composition which can be prevented from diffusing into the filling section (nonmagnetic layer).
A at least one polymer selected from the group consisting of a copolymer having a homopolymer and the unit structure having a unit structure derived from divinyl aromatic compound, or a polymer and a photopolymerizable compound and comprising a photopolymerizable coating material containing a mixture of, and flattening film forming composition for a hard disk which is characterized by containing a benzene ring per mole 1-90 mole% vinyl groups in the coating material object. Photopolymerizable compound is a compound having an acrylate group, methacrylate group, or vinyl group. Polymer is a copolymer further comprising an addition polymerizable compound as a copolymerization component. The first step, second step, the manufacturing method of a hard disk including a third step of exposing the flattened magnetic material surface by etching for covering the unevenness in the planarizing film forming composition for forming irregularities on the magnetic material.
.FIELD 1