It is an object of the present invention to provide a process for producing nano-particles, capable of efficiently producing monodisperse nano-particles substantially uniform in particle size and composition, and freely controllable in particle size and composition at low cost. The process for producing nano-particles comprises a particle precursor capturing step in which a liquid containing the particle precursor is incorporated in another liquid containing dendritic branching molecules to capture the particle precursor by the dendritic branching molecule, and particle forming step in which the particle precursor captured by the dendritic branching molecule is transformed into the particle.