This study aimed to determine science teacher candidates' understanding of the wave concept under the headings of the essential characteristics of waves and their place and importance in daily life. The research was carried out with 53 science teacher candidates studying in the first grade in the education faculty of a state university in Turkey in the 2021-2022 academic year. The research used a criterion sampling method to determine teacher candidates. It also employed the case study method, one of the qualitative research methods. To determine the opinions of teacher candidates on the wave concept, researchers developed data collection tools containing ten open-ended questions. The questions in the form, a data collection tool in this study, were prepared to include conceptual, transactional, and relational categories. Three questions were conceptual, four were transactional, and three were relational. Evaluating the study's findings in general terms, we can conclude that the candidates knew the concepts related to the wave. Still, they were not successful in explaining the wave concept, classifying them according to physical characteristics, and indicating the characteristics of wave types.