(EN) Disclosed herein are a high-density recording medium, such as a high-density optical disc and a recording and/or reproducing device therefor. At a transition area of the high-density optical disc allocated between a clamping area and an information area of the high-density optical disc is formed a step having a prescribed slope so that the high-density optical disc does not collide with an objective lens of an optical pickup provided in an optical disc device although the objective lens of the optical pickup is upwardly moved toward a recording layer of the high-density optical disc until it moves to the maximum working distance when the high-density optical disc, such as a Blu-ray disc, is improperly placed on a turntable provided in the o...
