The purpose of this study is to explore how high school physics teachers perceive and understand fundamental physical constants as well as how they explain them and what methods they currently use in class. This study developed a questionnaire survey to recognize physics teachers` level of understanding of fundamental physical constants, which were measured by many scientists and contributed the to generation and improvement of scientific theories. Those questionnaire surveys were conducted among 130 high school physics teachers in Seoul, Gyeonggi, and Incheon. Among them, 124 participated in the survey and six were interviewed. The content of the survey consists of three parts: (i) basic questions about teachers, (ii) questions to measure the teachers` understanding of fundamental physical constants, and (iii) questions about the educational use of fundamental physical constants. The survey was distributed via e-mail, and respondents submitted their responses via e-mail as well. Semi-structured interviews were conducted for 30 minutes each, and all interviews were recorded, transcribed and analyzed twice.