Media development courses are one of the main subjects in the structure of the education curriculum for prospective physics teachers. In this course, students are provided with adequate skills about the media and its development principles. One of the skills that can be trained in media learning is the ability to argue. The purpose of this study was to examine the effectiveness of project-based learning in media development subjects on the argumentation skills of prospective physics teachers. The mixed method was used in this study. There are three classes of students involved, where each class consists of several groups. Each group produces one product from a learning media project. Each group presents the resulting media. Data was collected using observation sheets, interviews, focus group discussions, and written tests. The results showed an increase in the argumentation ability of prospective physics teachers. They can convey the details of the project, express their opinions, and maintain their ideas logically.