1. Introduction: Femtosecond laser direct writing by photoreduction is powerful method to fabricate 3D metal structures that provides submicron to several tens of nanometers in fabrication resolution. Pioneering studies on the fabrication of metal structures inside soft materials, such as gelatin and flexible polymer, have been reported recently; however, inefficient two-photon absorption of near-infrared wavelengths to metal-ion-containing materials limits fabrication throughput and robustness of formed structures. In this study we demonstrate high throughput fabrication of metal structure inside a flexible material by using 522 nm femtosecond laser pulses, which efficiently interacts with the materials by two-photon absorption. 2. Materials & Methods: Poly(ethylene glycol) diacrylate (PEGDA, average molecular weight 6000) was used for the hydrogel material in this study. The hydrogel was immersed in silver nitrate solution to allow absorption of silver ions. Femtosecond laser pulses were focused into the hydrogel by using an objective lens to reduce silver ions to form a silver structure. The laser wavelength and the repetition rate were 522 nm and 63 MHz, respectively. The focused laser beam was scanned two dimensionally using x-y stage and Galvano scanning system. 3. Results & Discussions: Figure 1 (a) shows the transmission optical microscopy image of the line-shaped silver structure fabricated inside the hydrogel by using 522 inn femtosecond laser pulses at different scanning speeds. The scanning speeds were 10, 25, 50 and 100 μ/s in order from above. The width of the line structures decreases with increasing speed. Figure 1 (b) shows the transmission optical microscopy image of C-shaped structure fabricated inside the hydrogel by using galvano scanning system. The optical microscopy image shows that metal structures can be fabricated not only as 1D lines, but also arbitrary 2D patterns. 4. Conclusion: The line-shaped structures fabricated by using 522 nm femtosecond laser are much more uniform compared to that with 800 nm wavelength which we previously reported. The C-shaped structure was fabricated with Galvano scanning system. This method is promising technique for fabrication of metamaterials or micro/nano structures for electronic and optical devices. Detailed -results with discussion will be presented at the conference.