The purpose of this study is to investigate the influences of water environmental program using PBL on pro-environmental behavior for 4th graders in elementary school. The results of this study are as follows. First, the experimental group is more effective in promoting the pro-environmental attitude compared with the control group. Second, the experimental group is more effective in promoting the pro-environmental behavior compared with the control group. Third, the experimental group is not more effective in promoting the pro-environmental knowledge compared with the control group. Fourth, students are concerned and interested in the environment and environmental problems of the daily-life. And, they presented positive attitude and active participation toward environmental preservation. So, the process of PBL using water environmental program showed that it promotes active learning participation and various action. In conclusion, the environmental education program through PBL program has a positive effect on pro-environmental attitudes and behavior of elementary school students. It is demanded that more intensive research on this study should be done, linking with teaching and learning method, as a follow-up activity.