Research on teacher education assumes pedagogical content knowledge (PCK) to be a core component of professional competence that predicts both the quality of teaching and the achievement of teaching goals. In the field of physical education, there are some empirical approaches to describe PCK; however, an instrument assessing PCK, which factor structure has been empirically analyzed, is still missing. The current study assesses PCK via 40 items. All items comprise realistic teaching scenarios within one of eight movement fields and demand to support learners, to explain learning difficulties or to formulate appropriate instructions. After a satisfactory expert rating, 290 students studying to be physical education teachers answered the items. Results indicate that PCK can be measured by the factors supporting learners, explaining learning difficulties and formulating learning instructions. The factors correlated with medium to high effect sizes. Furthermore, the teacher students' semester predicted PCK, whereas the grade point average did not. This finding supports the qualification hypothesis. Overall, with regard to students learning to be physical education teachers, the study provides one of the few instruments that has been empirically tested.