Novel metal nanoparticles or nanowires have attracted an attention in physics and chemistry because of their unique characteristics on electrical conductivity and electrical field enhancement by localized surface plasmons. However, the simple and cheap fabrication methods have not been available so far. At LAOTECH in AIST, an easy but very valuable method was developed by the chemical decomposition of silver oxide thin film in a gas mixture of hydrogen and oxygen. By controlling the gas mixture ratio and pre-treatment of a vacuum chamber, we can convert the silver oxide film into 3-dimentionally deposited silver nanoparticles (each diameter~20nm) or nanowires.