To provide a magnesium alloy which contributes to production of a magnesium alloy extruded product, based on the development of extrusion technique and bending technique necessary for the production of a magnesium alloy sheet frame, to thereby achieve maximum weight reduction effect in the production of the vehicle sheet frame by using the magnesium alloy extruded product, compared with a conventional product formed of a steel material, an extruded aluminum alloy, and a magnesium alloy cast material, and to provide a method of producing the vehicle sheet frame using the magnesium alloy.

The vehicle sheet frame is produced by carrying out the following steps. In the first step, an AZ31 magnesium alloy is charged into a stainless steel container and melted at a predetermined temperature, and thereafter a billet for extrusion is produced by water-cooling. In the next step, the billet is extruded into a product having a predetermined shape while adjusting the temperature of a mold, the container and the billet. In the last step, the extruded magnesium product is formed into the shape of the sheet frame through a bending step and a stretching step.