The learning process in biology education takes place with the snowball effect. The slightestscientific mistake grows over time and prevents new information from being learned. In thisstudy, it was aimed to determine the misconceptions of pre-service science teachers aboutthe concept of organelle and the sources that caused them. The research, using the casestudy, was conducted in 2020-2021. The study group of the research consists of 54 pre service science teachers who were studying at a state university in Turkey. The structuredinterview form prepared by the researchers was used as the data collection tool. The analysisof the data was done by two different researchers using the content analysis method. As aresult of the research, it was determined that pre-service science teachers have a scientificdefinition of the concept of organelle and misconceptions about organelles in the cell. Whenthe reasons for these misconceptions are examined, it is determined that teachers, textbooks,supplementary books and technological applications are effective. According to the resultsof the research, it can be said that the misconceptions of pre-service science teachers about the theme of organelle should be eliminated. In addition, it can be suggested to work on thedetermination and correction of scientific mistakes in textbooks, supplementary books andtechnological applications that cause misconceptions.