Various efforts have been attempted to activate online community activities. In the case of activating online community with similar interests or hobbies, it requires not only activating the communication but promoting the subject. In this study, the authors propose the activating methods of the online community with the theme of pro-environmental behavior (PEB), using the compliance-gaining strategies which based on six principles of social psychology. They are reciprocation, commitment and consistency, social proof, liking, scarcity, and response expectation. In order to
examine this method, a case study was conducted where the method was introduced to an inactive online community with 10 participants. As the result, it was found that the messages posted to the community maintained and their PEBs were significantly improved.