The purpose of this study was to investigate the perception of high school students on informal science learning and career exploration through volunteering as a docent in a science museum. For this study, group interview data were collected from 15 high school students who participated as a volunteer docent in an exhibition, Feynman’s Talk on Physics, and the field notes from museum staff. As a result, the student docent showed the convergent understanding of atom through the experience of informal learning in the science museum and a positive perception of informal learning through the connection and differentiation with formal education. Furthermore, they came to have stronger interest and confidence in science, beyond the understanding of science concepts through a volunteer student docent activities. They also responded that communication with visitors affected on school achievement. Finally, they had a chance of career explorations to understand the practical job as an expert in a science museum, while learning about the daily life and accomplishments of the scientist.