Friction stir welding (FSW) is a welding process that utilizes the rotation of the tool to produce heat that is used to connect the material to be joined. This study aims to determine the effect of tool rotational speed on welding double-sided (double sided) 1xxx series aluminum material and 5xxx series aluminum material. Welding is carried out with 910 rpm, 1500 rpm, and 2280 rpm rotational speed with a feed rate variation of 60 mm / min and a slope angle of 1˚ and a depth of 4mm and 2mm pintool burping. This study conducts four types of testing, namely, testing the macro and micro structures, hardness testing, and tensile testing of welding results. The test results show the correction value in the reverse region of 66.8 VHN is higher than in the developed area of 38.7 VHN because it uses a different aluminum material and at each rotating speed seen its value rises in the Stir Zone and HAZ regions this is caused by the specimen point process seen from the microstructure image there is a cavity / pore so its value rises. The tensile strength value at a rotating speed of 910 rpm get a UTS value of 111.94 MPa. While the lowest stress value at 1500 rpm rotational speed is 92.44 MPa because it is considered to be a cavity that forms coarse grains in the specimen thereby increasing brittle sculpture. Microstructure construction with a variation of 910 rpm welding area produces more granules from the aluminum precitition process increasing tensile and hardness properties better than other rotational speeds more granules in the welding area stir then higher tensile and hardness.