Micro-tribology is a key technology in micro-machine. Atomic-scale wear and friction fluctuations degrade the performance of micro-machines. New wear-resistant, low friction materials should be useful in reducing micro- and macro-tribological wear and friction fluctuations. Our investigation of the frictional characteristics of polished CVD diamond films by FFM (friction force microscope), AFM (atomic force microscope) and conventional reciprocating tribometer and trial micro processing of diamond produced three main results. First, the friction coefficient of diamond film increases rapidly with decreasing load in the micro-load region. This is partially due to the surface tension of adsorbed water on the surface under high humidity. In the macro-load region also, the friction coefficient increases with decreasing load, but, in this case it is due to elastic deformation. The second result is that diamond film has excellent wear resistance in the micro-load region compared with silicon and diamond-like carbon (DLC) film. Finally, a micro-diamond gear and diamond shaft were fabricated by laser machining and thermo-chemical etching, and then assembled.