The subject matter 'alimentary rites' is one of the debates in religions and philosophical schools, and among a large number of the pious, some types of meal have been included the taboos and moral vice, so that the two opposing beliefs and two groups of followers associated with this debate are divided by a thick line. Aside from the moderate ranges that stand in the middle of this line, in some of these religions, systematic, complex and detailed instructions and recommendations have been compiled in condemning to eat meat. In a vast variety of the religions that have recommended or commanded vegetarianism, reasons such as Ahimsa, preserving the environment, physical and mental health, or respecting animal rights and observing the law of Karma have been considered. But another reason for embracing this way of life can be seen particularly by Manichaean elites, which goes back to the philosophical, viz. theological approach of this religion. In this study, an attempt is made to inspect the main grounds of vegetarian doctrine of Manichaeism, according to the philosophical system as well as theological and cosmological principles of this religion, and to provide the religious and cultural roots of this 'obligation'.