Our purpose in this study is to clarify what kind of knowledge or education promotes environmentally responsible behavior. Suwa et al. (2006) used a questionnaire to survey people’s environmental perceptions and environmentally responsible behavior and developed an environmental behavior model. Using their model and applying path analysis to the results of the survey, they found that awareness of cost is the most influential factor in promoting environmentally responsible behavior. Based on the findings, we hypothesized that understanding the structure of social dilemma raises people’s awareness of cost and encourages them to behave in environmentally responsible ways. To test the hypothesis we then proposed a social dilemma education program that raises awareness of cost, and compared it with existing environmental education. Our results showed that our social dilemma education program increases awareness of cost and results in concrete environmentally responsible behavior, but that existing education does not.