As the demand for car industry increase worldwide and car models diversify, industry of automobile parts also keep pace and grows day by day. However, since industry of automobile parts is staying small and there are only few study on basic knowledge of productivity, financial competitiveness is greatly insufficient. Among accessory processing, there are more parts such as key home or bolt hole rather than general turning operation, therefore, currently study on intermittence process is exigent. This thesis studied on machinability of Ductile cast iron(FCD 500) which is used for car break desk to help this kind of situation. Also it studied machinability by using Taguchi method which can get the best performance with few tests.