This study aimed to explore the science teachers' existing ideas about Inquiry-based learning as a way of enhancing students' inventive thinking skills. Methodology regarded interpretive paradigm. The first author participated in the STEM in-service teacher professional development project called the Inquiry-based learning workshops of the Thailand STEM Education Project of Chevron Enjoy Science. The first author as participant observer, therefore, would interpret teachers' existing ideas of ways of enhancing students' inventive thinking skills during their participation in the workshop. Key informants were 15 females and 5 males who participated in the Inquiry-based learning workshops of the Thailand STEM Education Project of Chevron Enjoy Science at Khon Kaen, Thailand. Teachers' existing ideas of ways of enhancing students' inventive thinking skills will be examined through their responding on the checklist about the five essential features of the Inquiry-based learning NRC (2000) and their sharing ideas on the open-ended questions about inquiry-based learning and enhancing inventive thinking. The results of this study are to be the evidence support of the researchers' belief that the number of Thai teachers hold some understanding of the inquiry-based learning which could develop some more ideas of organizing learning activities for enhancing the students' inventive thinking skills.