This study was conducted to determine the effect of environmental attitude, environmental concern, perceived seriousness of environmental problems, perceived environmental responsibility, perceived effectiveness of environmental behavior, concern for the self-image in environmental protection, and social influences on behavior of green purchasing behavior. This research employed a quantitative approach using surveys. Data was collected by questionnaire. The subject of this research is Millennials in Yogyakarta who have exhibited previous green purchasing behavior. The sample of the research are 120 respondents. The sampling technique used is non probability sampling with purposive sampling. The analytical tool in the study was multiple linear regression analysis. The results of this study indicate that there are three main factors that influence the behavior of millenials in purchasing green in Yogyakarta: social influence, awareness of self-image in environmental protection and environmental awareness. While environmental attitude, perceived seriousness of environmental problems, perceived environmental responsibility and perceived effectiveness of environmental behavior has no influence on purchasing green.