The invention provides a method of manufacturing nickel nanoparticles and nickel nanoparticles thus produced, having superior dispersion stability and smooth surface, by reducing after forming nickel-hydrazine complex in a reverse microemulsion, wherein the method includes (a) forming an aqueous solution including nickel precursor, surfactant, and hydrophobic solvent, (b) forming nickel-hydrazine complex by adding a reducing agent that includes hydrazine to the mixture, (c) producing nickel nanoparticles by adding an reducing agent to the mixture that includes said nickel-hydrazine complex.