Nanostructure has been introduced into thermoelectric (TE) field. And high performance TE devices with nanostructure have been reported. Furthermore, Bismuth Telluride (Bi_2Te_3), one of TE materials, has been studied long time and shown the highest efficiency around room temperature. Therefore, it should be expected that Bi_2Te_3 film within nanoparticles (NPs) is high potential TE composited material. We have utilized Bio Nano Process (BNP) in this study. BNP is using ferritin, and that can fabricate the NPs in uniform size and distribute them.