This essay explores the religious motivation behind vegetarianism. By using in-depth interviews with religious vegetarians in Taiwan, it will discuss the religious elements behind interviewees’ vegetarian diet. Most of the interviewees are devotees of Buddhism, Yiguangdao or Chinese popular religion and the discussion in this essay will be divided accordingly. This first chapter is Introduction, in which I will discuss my research motivation, literature review, and research method. The second chapter will focus on religious discourse of Buddhism, Yiguangdao and Chinese popular religion on vegetarianism. The third chapter will investigate the process of interviewees’ conversion to religion and their experience with vegetarian diet. The fourth chapter will analyze and discuss the interviewees’ claimed reasons to vegetarianism. I will divide their answers into three categories, “Metris and karma’, ‘spiritual practice and religious precepts’ and ‘right to life and environmental ethics’, for discussion. The fifth chapter is conclusion. This essay will argue that for vegetarians with a religious background, the traditional religious discourse such as compassion, karma, precepts, etc. are the main motives for their vegetarianism. As such, when their vegetarianism challenged, religious belief can be a strong support to continue their vegetarian diet. Other secular but popular discourse such as environmental ethics and health are usually added values and not emphasized. Therefore, religious discourse is the main motive behind the interviewees’ vegetarianism.