We have designed and developed a spatial light modulator named LCOS-SLM (Liquid crystal silicon-spatial light modulator) to achieve pure, linear and precise phase control with high diffraction efficiency. We have applied this device for fundamental research of singular optics and several practical applications as laser machining, microscope, and adaptive optics. In this paper, we introduce basic characteristics of LCOS-SLM and some experimental results on the research and the applications.