Generally industrial multi-articulated robots are used for parts assembly, welding, and painting processes. The high flexibility of them is very useful to not only parts assembly, welding, and painting processes, but also machining processes. But because of machining processes to need a high stiffness of machine structure, so machining is usually not tried at them, except deburring processes now. During past three years the works are carried out to improve the stiffness of a industrial multi-articulated robot With some gas spring as a first idea in this research area. As a result of that stiffness was significantly up, and found and investigated the machining possibility at it.