Mirror-polishing processes have recently been required to add high quality, high-precision precision and multi-functionality to industrial products. However, this requires skilled manual work, making it difficult to improve productivity. Automatic polishing of these products is also very difficult. Furthermore, mirror-polishing process of stainless steel, titanium and glass, which are often used in high-value-added medical products, is also difficult. Therefore, in this study, a technology for high-precision, automatic mirror polishing of three difficult-to-polish materials - stainless steel, titanium and glass - was developed and evaluated. First, the difficult-to-polish properties of different materials were considered, and then tools were developed to improve these properties and enable suitable mirror-polishing processes. Next, a polishing slurry was developed to improve the surface roughness (Rz=0.1 µm or less). Finally, the optimum polishing conditions for the proposed mirror-polishing process were determined by design of experiment and then evaluated. It was concluded that;(1) In order to perform mirror-polishing processes of three types of workpieces, stainless steel (SUS304), titanium (pure titanium) and glass (quartz glass), new polishing tool and slurries corresponding to each material were developed and the optimum polishing processing conditions were clarified, (2) Using (1), mirror-polishing processes of each material with a surface roughness of Rz=0.1μm has been achieved.