Energy harvester is a key device for realizing trillion sensors network society. Thermoelectric generator (TEG) is regarded as the ultimate energy harvester to provide semipermanent power from heat energies via Seebeck effect. The recent discovery of the superior thermoelectric (TE) property of silicon nanowires (Si-NWs) opens the way for Si-based TEGs. In this paper, a very simple device architecture of Si-based micro TEG is proposed. It can be fabricated by the CMOS-compatible process, and the TE power density is found to be scalable by miniaturizing and integrating the structure.