In this article, Mulla Sadra’s account of the problem of evil is considered. He is one of the philosophers who attempt to provide logical solutions for the problems which stem from divine attributes (omniscience, omnipotence and goodness) by appeal to the bases of Transcendent Philosophy and thus defend God’s omniscience, omnipotence, goodness, wisdom and defend this world to be the best possible one. The most basic factor in answering the doubts in this respect is principality of existence and his basic solutions in this respect, as in the case of some Greek philosophers such as Plato and Aristotle, follow the model of understanding evil to be nonexistent and accidentally made. Mulla Sadra’s innovation, however, is his use of the principle of principality of existence and its equivalence to goodness. Moreover, he makes use of a priori and a posteriori arguments to solve the problem. Therefore, by solving the problem of evil, he suggests solutions for the problem of dualism and gives way to monotheism. We provide this discussion in following article.