Many devices and systems can be miniaturized using Micro-Electro-Mechanical Systems (MEMS) technology. Micro pressure sensors and micro accelerometers (air bag sensors) are examples that are widely commercialized. In the case of optical systems, some optical components need combining to implement the function desired for optical processing. Micro-optical-bench based on silicon surface and bulk micromachining has been proposed in order to integrate optical components on a silicon substrate. Optical data storage is a promising industrial field to which the micro-fabrication technology can be applied. High integration of optical and mechanical components is needed for the optical head of data storage in the next generation. A light optical head with micro-lens and micro-actuator for focusing and tracking can be fabricated by MEMS technology. Furthermore, the diffraction limit in the optical storage using a lens can be overcome by the near-field optical technology. The optical storage system with a multi-probe array based on the near-field scanning optical microscopy (NSOM) also attracts a high level of interest. In order to study MEMS technology from the basics to applications for optical data storage, the fundamental processes in silicon micromachining and the integration techniques for micro optical components are presented. Microfabrication of the conventional optical and mechanical components for data storage and future technology such as NSOM is also included.