Environmental education aims to solve a variety of problems around all kinds of pending environmental issues. In South Korea, environmental education has developed in a dual system between school environmental education provided by environment teachers as part of the school's subject curriculums and social environmental education provided by environmental education instruction in the community outside the school. Today school environmental education has shrunk considerably while needs for environmental education in the community grow day by day. In this situation, environmental education instructors outside the school provide students with environmental education by visiting schools themselves as well as in the community outside the school, covering most of practical environmental education for students. In the area of education, there have been no full researches on environmental education outside the school and especially environmental education instructors providing the education. This study thus set out to investigate the educational experiences of environmental education instructors by selecting four environmental education instructors as research participants and conducting an in-depth interview with them in June~September, 2021.
 The findings show that environmental education instructors took various chances to begin providing education and there was a high degree of diversity in the content of education and the aspects of growth through educational experiences among the instructors. These findings once again demonstrated the value of diversity that environmental education should guarantee. The environmental education instructors all made many efforts to provide the right education on all sorts of discriminating environmental matters while pursuing diversity. A high level of spontaneity demonstrated by the instructors in the process became an important foothold for their self-growth. The uniqueness of individual environmental education instructors was reflected on environmental education in various ways, and their enriched educational experiences added further diversity to their unique educational capabilities. These findings raise a need for social and educational supports to help the content and methods of environmental education develop in a productive manner in harmony with the uniqueness of environmental education instructors. It is also needed to provide institutional supports for the management of environmental education to guarantee diversity and flexibility like today and, at the same time, ensure systematic long-term education.