The aim of this study is to determine the opinions of pre-service elementary school mathematics teachers about misconceptions. For this purpose, case study, which is one of the qualitative research methods, was used. The study was conducted with 54 pre-service elementary school mathematics teachers. The data collection tool of the research consists of written response papers that they give to open-ended questions asked to participants. The views of pre-service elementary school mathematics teachers to open-ended questions were analyzed by content analysis. In order to prevent misconceptions that may arise during the lesson, pre-service elementary school mathematics teachers stated that they would; investigate the misconceptions, prepare for the lesson, study the subject, concretize the subject, visualize, determine the pre-learning, give daily life examples, etc. In order to determine whether their students have misconceptions, they stated that they would ask questions, evaluate the answers, solve the test, examine the mistakes and questions, observe the reactions, etc. It is recommended for further research to examine how pre-service elementary school mathematics teachers take precautions to avoid misconceptions by preparing a lesson plan, and to examine the situations of determining and correcting mistakes in students by observing the lessons of the teachers.