Analysis of Argumentation in Socio-Scientific Issues of junior High School Students. The 21st Century Education focuses on the development of the competence in creativity, critical-thinking, communication, and collaboration. Based on that reason, the argumentation can be one of the solutions to answer this issue since it facilitates the critical-thinking and communication competences. Arguments can be used in socio-scientific issues that present open problems and debatable. The aims of research is to find out the quality of the argumentation on the socio-scientific issue through the plastic theme of the topic of pollution. Argumentation analysis using TAP (Toulmin's Argument Pattern) consisting of 6 components, namely claims, data, warrant, backing, qualifier, and rebuttals. Based on the results of the research, it was found that the quality of the argumentation in the socio-scientific issues of junior high school students was still low. The low quality of argumentation is caused by the poor of students' concept understanding.