PROBLEM TO BE SOLVED: To provide an implant piece for nerve implantation, which has necessary flexibility and strength and can efficiently reproduce a nerve in an implantation region.SOLUTION: A nerve fascicle is formed by bundling together two or more micro-fibers including a nerve stem cell or cells obtained by differentiating the nerve stem to a predetermined stage. The micro-fibers are obtained by coating micro-gel fibers including a nerve stem cell or cells obtained by differentiating the nerve stem to a predetermined stage with high-strength hydrogel, and the two or more micro-gel fibers are bundled by coating with biocompatible gel.
