An optical information recording/reproducing apparatus for recording information on a recording medium and/or reproducing information from the recording medium, includes: a laser light source for performing recording and/or reproducing information; a shielding part, using a liquid crystal, that can switch between transmission and interception of laser light emitted from the laser light source; a driving circuit for driving the switching between transmission and interception of the shielding part; a moving part for relatively moving the shielding part and the laser light; and a controlling circuit for controlling the moving part. The moving part relatively moves the shielding part and the laser light so as to switch a region to which the laser light is applied from a first region of the shielding part to a second region thereof different from the first region, in order to prevent the liquid crystal from deteriorating.