The present invention provides an optical recording medium and an optical disk device realizing prevention of crosswrite and uniformity of playback signals and capable of easily securing compatibility with a read only disk. It provides an optical recording medium on which light LB condensed by a lens (12, 14) having a numerical aperture of 0.850.1 and a wavelength of 4055 nm is focused for recording or playback, having a substrate 1 formed with a groove 2 in its surface, an optical recording layer 3 formed on the substrate and having topography corresponding to the groove, and a light transmission type protection layer 4 formed on the optical recording layer; used when light for recording or playback is focused from the protection layer side to the optical recording layer; using as a recording area only the optical recording layer of one of a side far from the emitting side of the light for recording or playback, that is, a portion corresponding to a recessed portion of the topography, and a side close to it, that is, a portion corresponding to a projecting portion; having a track pitch of 0.320.01 m; and having a depth D2 of a recessed portion with respect to a projecting portion in the range of 19 to 24 nm.

 
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> Information recording and/or reproducing apparatus, information recording and/or reproducing method, and phase-change recording medium for use in the apparatus and the methods

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