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