Introduction: In this comparative research, while discussing free will as the basis of moral action, Mulla Sadra's and Kant's views were examined. In examining Mulla Sadra's views, his fundamental approach in relation to free will and the fruit of practical reason, i. e. the attainment of transcendental agency, has been considered as the main paradigm. Material and Methods: The research method is logical analysis on the use of library texts. Conclusion: From the comparison of these two theories, it can be concluded that Kant's theory has led to humanist ethics due to benefiting from the essence of human knowledge and using elements such as independence of will. Because according to Kant, man has a true identity and is free from all external and transcendental factors. According to him, independence of will is the highest principle of morality. Mulla Sadra's theory is an epistemological-divine theory and his epistemological basis is also rooted in the beyond. From his point of view, although man is a creator, but he is really the same as belonging, needing, and connecting with the origin of existence, that is, God, and Mullah Sadra's upward course is based on the movement of his essence, the originality of his existence, its skepticism, and the connection of man with the holy intellect and the active intellect, and finally it shows communication with God,that man has no independence from himself and his whole existence is mortal in the existence of the Almighty. Kant considered will and free will as the most fundamental bases, while Mulla Sadra considered theoretical reason to be the basis of human knowledge.