Due to the environmental problem like as CO2 emission, energy problem and etc., many car makers are trying to reduce the weight of the vehicle. The most effective way to reduce the weight of vehicle is to use lighter materials, aluminum, magnesium, plastics. And weight reduction of body is more effective than the others. There are two kinds of lightweight body, aluminum monocoque body and aluminum space frame body. Aluminum space frame body has many advantages from the space frame structure and the use of lighter materials. So, many car makers are developing aluminum space frame body and in mass production of some kinds of car, eg. Sports car, electric vehicle and etc.For these reason, we have developed and aluminum space frame body vehicle with ATOZ model base. Using FEM analysis, we designed sections of extrusions(6061) and fabricated spaceframe skeleton by ARC welding. And we used some castings such as B-pillar(post), shock absorber housing(shock tower) and 5 kinds of cast nodes to get higher joint stiffness. Outer panel and moving parts were fabricated by plastic composites using hand layup method. We could get 60kg(23% weight reduction based on body weight) of weight reduction and we expect get higher level of weight redution (above 40%) through the optimization of the current design. To achieve this goal, we are in design optimization using FEM analysis.