The superposition principle is used to explain many phenomena in physics. Incomplete knowledge about this topic at a basic level leads to physics students having problems in the future. As long as prospective physics teachers have difficulties in the subject, it is inevitable that high school students will have the same difficulties. The aim of this study is to determine the misunderstandings and ideas of prospective physics teachers about applying the superposition principle to waves moving on a continuous rope. Firstly, the related literature was reviewed and then an eight-question test including drawings was prepared. The test was reviewed by three experts and necessary corrections were made. In order to make the content of the test clearer, the test was given to two students as a pilot study. The test was then applied to 1st, 2nd, 3rd, 4th and 5th grade prospective physics teachers of Buca Education Faculty, Dokuz Eylul University. The total number of students was 147, of whom 21 were also interviewed. Analysis of the drawings and ideas of the students reveals that the prospective physics teachers have problems in applying and understanding the principle.