The aim of this study is to identify the reasons why pre-service physics teachers have difficulties related to special relativity topics. In this study conducted with 25 pre-service physics teachers, the case study method, which is a qualitative research method, was used. Interviews were held with the participants about their reasons for difficulties in understanding special relativity topics. We used content analysis with the interview data and created eight categories. By doing so, we tried to identify the causes of difficulties experienced by the participants. As a result, it can be said that students are biased against relativity subjects and consider them to be difficult. Although the students found the subject interesting, problems such as mathematical difficulties, problems related to determining the reference system and transition from classical physics to relativistic physics made the learning process difficult for them. Additionally, we identified positive and negative opinions about the teaching method.