Abstract: Disclosed herein is a metal nanoparticle whose surface is coated with a silicon oxide. The silicon oxide is obtained from a silicon compound or a derivative thereof as a precursor and has a particle diameter of a few angstroms (A). Further disclosed is a method for manufacturing metal nanoparticles. The method comprises the steps of a) mixing metal ions, a solvent and an additive required for forming metal complex ions, b) adding a silicon compound or a derivative thereof as a precursor for forming silicon oxides, to the mixture of step a) to coat the surface of the metal ions, and c) adding a reducing agent to the mixture of step b) to reduce the metal ions. If necessary, the method further comprises the step of d) lyophilizing the resulting product of step c), i.e. metal nanoparticles. Since the surface of the metal nanoparticle of the present invention is coated with a silicon oxide, the metal nanoparticle is stabilized.