For low environmental load and decreasing waste fluid disposal cost, the electric rust preventive machining method that uses only water as machining fluid has been developed. However, there are several problems for this practical use. In this investigation, for using this method in various regions of the world, reset and synthesis of water quality that is different in regions for containing impurity ingredient and water hardness is examined. At first, water is deionized and purified with water refine recycle system. Afterward, synthesized water is reproduced. Hardness and conductivity is adjusted in water by addition of very small amount of natural hardness ingredient CaSO 4. Consequently, even if water is different, constant quality of the water can be always secured anywhere in world. Furthermore, electric rust prevention is achieved 3hours with adjusted 100μS/cm synthesized water. However, adhesion derived from anode is appeared in workpiece 2hours. It is possible that the electric rust preventive machining can be carried out stability anywhere in world.