Soluble Cutting Fluids (SCFs) have been used in metal machining processes to improve the quality of metal processing equipment and products. Although SCFs are useful and essential material, wasted soluble cutting fluids are harmful in hydroecological systems because of the high concentration of COD and nitrogen material. If discharged to hydroecological systems without specific treatment, they may cause eutrophication in rivers and lakes. Therefore, the removal efficiency of the COD contained in the SCFs is investigated in this study using electrochemical treatment with an insoluble electrode. The electrode was made of titanium with iridium plating, made from a perforated metal sheet to agitate the sample in the reactor. Cathode and anode electrodes were inserted into acrylic reactor alternately and the reaction time was one hour. The experimental results were as follows: First, for 60 A/m2, 80 A/m2, and 100 A/m2 current densities, the COD removal efficiencies were 42.0%, 63.9%, and 78.4%, respectively.