In this study, the curvature FSW experiments were performed with the 2 mm thickness of Al 5083-O using by the 5 axis(X/Y/Z/A/C) position control system. For the mechanical test of the butt joints, the tungsten heavy alloy as the tool material without necessary after finishing the heat treatment such as quenching was used. In particular, the insertion depth and the welding speed was changed at the constant rotation speed in order to select the optimum FSW condition. The test results were visually satisfactory for the approximate joint length of 300 mm. Sound joint was formed at the condition of 1.9 mm-1000 rpm-100 mm/min and its tensile strength of joint was the most high almost the same as that of the base material.