Friction stir welding (FSW) welding is a connection process that can connect similar or not similar materials by utilizing heat energy that comes from friction and produces high temperatures so that it can melt the material and make the material connected. Polypropylene (PP) materials are among the lightest materials and have advantages such as tensile strength, flexural strength, and high rigidity and avoid corrosion. lack of PP material which is at low hardness, and impact strength is not good at low temperatures. This study was conducted with the aim of obtaining the optimum tool pin rotation on the FSW welding joint PP material which has a thickness of 5 mm by varying the pin rotation of the tool. This study uses materials from plastic, namely polypropylene sheet with dimensions of 5 x 100 x 80 mm, using M3 cylinders and 4,7 mm pin length. The parameters used for variations in pin tool speed are between 588, 977, 1562, 2371 RPM and constant welding rates of 9.5 mm / min. Welded joints use a type of butt joint. This study uses macro testing, shore durometer hardness test and tensile testing using ASTM D638 type I standard. The results of the research showed that the results of the tensile test where the best results were obtained at the 977 RPM tool round of 28.69 MPa. In the shore durometer hardness test where the best results were also obtained at the tool rotation 977 RPM in the retreating section 60.5, stir zone 55 and advancing 59.5. The results of macro structure testing obtained several defects such as flash, porosity, and void.