A State of the art of MEMS (Micro-Electro Mechanical Systems) is described in the fluid engineering based on the survey report on the micro EFD in JSME, P-SC298. The problems of the compressibility and the boundary condition in the MEMS are introduced. The development process of the micro device in the MEMS application is also discussed. The emphasis is placed on the integrated process of Computational Fluid Dynamics (CFD) and Experimental Fluid Dynamics (EFD).