A demand for lightweight parts of high strength has increased by the rapid development of technology for automobile and aircraft. In order to achieve the production of lightweight parts, the several techniques such as optimum design, development of lightweight material, process planning and die design must be mutually connected. The overall technology is to be established to manufacture a product using semi-solid forging which is one of the methods manufacturing the closest product to the final shape from the raw material. Therefore a large number of studies related to the semi-solid forging has been actively progressed for last twenty years in order to improve the formability of the above material and form parts having high strength. This paper presents the procedure of process to manufacture a product using semi-solid forging. The application of numerical analysis for flow simulation during the forming process is also investigated to design die gate. As an actual example, to manufacture a master cylinder of brake system in automobile is also shown by semi-solid forging. (Received January 6, 1999)