Technology of Friction Stir Welding (FSW) is a relatively new technique for joining metal. In some cases on Aluminum joining, FSW gives better results compared with the arc welding processes, including the quality of welds and less distortion. The purpose of this study is to analyze the parameters effect of high speed tool rotation on micro Friction Stir Spot Welding (μFSSW) to the shear strength of welds. In this case, Aluminum material A1100, with thickness of 0.4 mm was used. Tool material of HSS material was shaped with micro grinding process. The spindle speed was fixed at 30000 rpm. Tool shoulder diameter was 3 mm, and a length of pin was 0.7 mm. The parameter variations used in this study were the variable of pin diameter (1.5 mm, 2.0 mm, and 2.5 mm), a variable of plunge speed (2 mm/min, 4 mm/min, 6 mm/min), and the variable of dwell time (2 seconds, 4 seconds, 6 seconds). Where the variation of these parameters will affect to the mechanical properties of welds (as response) was the shear strength. Response Surface Methods (RSM) was used to analyze μFSSW parameters with the shear strength of welds. From the result of experiment and analysis, it is shown that the important welding parameters in high speed μFSSW process are pin diameter and plunge speed.