Special relativity has been started to be taught in high schools in addition to universities. Moreover, it attracts the attention of scientifically literate individuals. The purpose of this study is to determine high school and university students’ levels of difficulty understanding of special relativity. Furthermore, if it made a difference according to gender or educational level was also searched. In our previous study, which formed a basis for this research, the students’ opinions about difficulty understanding were determined by the interviews. The opinions obtained from the previous research were compiled and a Likert test with 5 option was prepared. This scale was applied to 691 student (446 science teacher candidates and 245 high school students). When the data obtained from the scale with 23 items applied was analyzed, it consisted of three factors. These factors are the perception of the topic, mathematical difficulties and the teaching methods difficulties. According to the general results, the students think that this topic is easy as much as they think it is difficult. High school students remarked that they had more difficulties than the university students and women remarked that they had more difficulties than men from some points of view.