We developed in collaboration with Hyogo Prefectural Institute of Technology and Sakurai Industries Co., Ltd. technology for manufacturing large-sized products from the extruded noncombustible magnesium alloys through frictional stir welding (FSW) or laser welding without degrading merits of the materials. In this way, it has been made possible to build an automobile roof box, 2,000 (L) × 670 (W) × 270 (H) mm, from noncombustible magnesium alloys. The new technology allows reducing weight of a structure by about 25 % from that of comparable size made from fiber-reinforced plastics (FRP). It is expected that the technology is applied to the development of products with complicated 3D geometry from extruded or wrought magnesium alloy materials, taking advantages of superior properties.