Recently, the method of micro fabrication has been important in the field of manufacturing, and a demand on microfabrication has been increasing for a new micro functional devices such as photonic crystals. In this research, we propose a new method of microfabrication using a metal ion solution, a conversing laser and photocatalyst nano-particles. When a conversing laser is illuminated in the metal ion solution including photocatalyst nano-particles, the photocatalyst particles are excited and metal ions are expected to be reduced only at the vicinity of beam waist. Then, scanning beam waist, we can fabricate the three dimensional micro structures. In this report, we estimated a mechanism of this proposed method through some verification experiment and investigated the capacity of this method. First, we made a fundamental experiment by changing the wavelength of focused beam in the silver ion solution including TiO2 nanoparticles and investigated a proper wavelength of focused beam. Second, we made some verification experiments under variable solution conditions and investigated the role of each chemical reagent of solution. Third, we estimated the mechanism of this fabrication method by these experimental results. Finally, we developed the experimental system of automatically scanning the focused beam and fabricated some micro structures using this system. From these result, we indicate the capacity of this method which can fabricate the free-form curves and three dimensional lattice structures with the process resolution of several micro meters.