The purpose of this study was to develope an Inquiry-Based Environmental Education Program for Elementary School Students by Using DO meter based on the theory of the inquiry-based environmental education. The developed program consisted of 5 constituents of Environmental Studies for the Environmental Education (ESEE) and was applied to the 6th grade students of elementary school. The inquiry activities have been conducted around Gigyechon stream in Pohang city where the school was located. The evaluation form to evaluate the environmental education programs in the perspective of the Inquiry-Based Environmental Education was developed and used to evaluate after applying the developed programs. As a result, it was known that the developed programs have been well constructed and this program would help fostering the environmental understanding of the world. And also the inquiry-based environmental education was suitable for the environmental education targeting the elementary school students. This study has a significance in the perspective that the concept and the theory of inquiry-based environmental education has been realized into the program suitable for the elementary school students and that the new direction of the environmental education for the elementary school has been suggested. In addition, the developed evaluation form to assess the effectiveness of the program is expected to be helpful for the future studies related to development of the inquiry-based environmental education programs.