Provided is an optical information recording/reproduction apparatus in which a tilt margin in a radial direction of an optical disk is increased to thereby reduce a danger that the optical disk and a solid immersion lens come into contact with each other as compared with a conventional case. The optical information recording/reproduction apparatus of the present invention includes: an objective lens for condensing a light beam from a light source; and a solid immersion lens (SIL) that is disposed between the objective lens and an optical recording medium, in which a shape of a bottom surface of the SIL on a recording medium side of the SIL is formed such that a length of the bottom surface in a radial direction orthogonal to a track direction of the recording medium is shorter than a length of the bottom surface in the track direction.