In an optical recording/reproducing apparatus, and in particular to a head of an optical recording/reproducing apparatus, the optical recording/reproducing apparatus includes a slider at which an objective lens is installed at a top surface of the slider and a solid immersion lens (SIL) installation hole formed below the objective lens penetrates toward to the bottom surface of the slider in order to install a SIL; a flying device fixedly installed around the SIL installation hole at the bottom surface of the slider in order to lift the slider above an optical recording medium; wherein a sectional area of the slider parallel to a surface of the optical recording medium increases from the bottom surface to the top surface.