The electroless plating method has played an important role as an indispensable metallization technology for miniaturization of electronic components. This investigation discusses selective metallization on the fine area (nanometer size) by electroless plating. The experimental purpose is to fabricate a probe which is used for scanning near-field optical microscopy. The probe (cone angle 20 degrees, probe size 4 mu m) is comprised of an optical fiber covered with a metal film except for an aperture at the apex of the fiber. Nickel-plated probes with an aperture of 100 nm were fabricated by optimization of the plating conditions (dissolved oxygen concentration, bath temperature, and birth pH) and the addition of a catalytic poison into the plating bath.