In this paper, studies on silicon carbide (SiC) micromachining and micromachined gas turbines are described : (1) SiC micro-reaction-sintering combined with silicon lost mold method has been developed, and SiC micro-rotors of 5 and 10 mm in diameter were fabricated. (2) Deep reactive ion etching (deep-RIE) of sintered SiC is being studied. To date, the etching depth of over 100 μm was achieved at the speed of 0.48 μ/min. using an inductively coupled plasma RIE system with SF_6 gas. (3) Silicon micro-air turbines for rotating an integrated grid polarizer have been fabricated, and the rotational speed of about 10000 rpm was achieved. (4) A computer fluid dynamics (CFD) program is under development for numerical fluid analysis inside micro-gas turbines. The airflow inside the abovementioned micro-air turbine was 2-dimensionally calculated.