A metal-made high-precision gear and a gear mechanism are disclosed. The precision gear is made of a novel material which does not exist in conventional materials for precision gears, including resins and tool steels, has high hardness, strength and excellent surface smoothness, and is superior in workability. In the precision gear which is formed of an amorphous metal alloy having a ternary, quaternary or higher composition containing iron group elements, such as Fe, Co, Ni, and Cu, Ti, Zr, Hf, as the principal elements, the precision gear whose module is 0.2 or less is made of the amorphous metal alloy having a disordered structure which does not have a fixed regularity and whose XRD pattern is a halo pattern, namely exhibits a broad peak.