Control of optical properties of materials has been investigated for efficient thermal energy utilization. Applying the resonant effect between periodic microstructured surface structure and photons, the spectrally selective thermal radiation surface, this is so-called selective emitter, is made on Si and high temperature metals by means of micro-machining techniques. These selective emitters can be applied to Solar thermophotovoltaic systems selective solar absorber, and sky radiator etc. Thermal radiation spectra of the emitters are measured at high temperatures and selective emission due to the surface microstructures is clearly observed. Numerical calculations based on rigorous coupled-wave analysis (RCWA) are also performed to predict spectral properties of the emitters.