This study aimed to investigate changes in the understandings of the Nature of Science (NOS) of preservice chemistry teachers after participating in the explicit, reflective, and contextual NOS teaching. The sample of the study consisted of nine preservice chemistry teachers who attended scientific research methods course at the undergraduate level. The study was designed and conducted according to the qualitative research method. Preservice chemistry teachers' understandings of the NOS was collected through the "Views on the Nature of Science-C" (VNOS-C) questionnaire, which consists of 10 open-ended items. The questionnaire was translated and applied before and after an explicit, reflective, and contextual NOS teaching. The data were analyzed descriptively through the use of a rubric. To ensure the reliability of the collected data, interviews were also conducted with participants to clarify their answers to the questions. According to the results, it was determined that the majority of the participants had a very poor understanding of NOS before teaching. It was determined that changes in the understandings did not occur at the desired level for all NOS aspects despite some positive changes after the teaching.