We fabricated nanometric aperture arrays in order to apply to an optical probe in high-density near-field optical storage for increase of data-transmission rate. The aperture arrays were fabricated by forming concave pyramidal grooves on a silicon-on-insulator wafer with electron beam lithography and wet anisotropic etching. Modification of the apex shape of the grooves by re-oxidation and subsequent reactive ion dry etching was able to increase the uniformity of the aperture size remarkably. The Light transmission efficiency of the fabricated apertures was measured to be similar to 10(-3) when the aperture size was 100 nm which was higher than that of a conventional optical fiber probe by several orders of magnitude.