In the first embodiment, the barrier layer covers the surface and the outer and inner peripheral end edge surfaces of the recording layer, the inner and outer peripheral portions of the substrate and the cover layer adheres to each other in at least partial region thereof via the adhesive layer, and {HEAD ~ the maximum length} of {TAIL ~ this region} in the radial direction is 0.4 mm or more 
In the first embodiment , the barrier layer covers the surface and the outer and inner peripheral end edge surfaces of the recording layer , the inner and outer peripheral portions of the substrate and the cover layer adheres to each other in at least partial region thereof via the adhesive layer , and { HEAD ~ the maximum length } of { TAIL ~ this region } in the radial direction is 0.4 mm or more
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