In teaching mathematics, the teacher should pay attention to the quality of the problems to be used in the classroom. It is important for pre-service teachers to experience problem posing in order to create a rich teaching environment. In this study, the free problem posing situations of pre-service primary school teachers were examined in terms of mathematical process skills. Ten pre-service primary school teachers studying in the 4th grade participated in the research. This study, which was carried out through distance education in the 2020-2021 academic year, is action research, which is one of the qualitative research patterns. The data were obtained by the application of the problem posing test before and after the problem posing instruction. It was observed that there are misconceptions in terms of mathematical communication in the problems posed by the pre-service primary school teachers, representations that are not suitable for the students’ level are used, and mathematical symbols are written incorrectly. They generally posed the problems they related with real life. However, there were few instances where the problems were related to different disciplines that were not included before the application. Pre-service teachers generally posed routine problems that require analogy-based reasoning. Subject matter and curriculum knowledge of pre-primary school teachers can be improved by problem posing studies.