A finished product structure formed by In-mold decoration process includes an electromagnetic protective material, a bearing layer and a formed plastic material. The substrate fixed on the transfer unit is spaced from the organic layer deposition assembly while being transferred by the first conveyer unit. The gradients are generated in the partial section corresponding to a predetermined field direction, whereby the field direction differs from the channel direction. Thereby, even when reproducing the data in the data file from the optical disk in which the writing of the data in the data file is failed, the data in the data file can be reproduced with the rewritten data correctly.