Heidegger developed his view of freedom via discussing Kant's and Schelling's view of it. This paper describes Heidegger's view of freedom via his critique of Kant. Heidegger first proposed two kinds of freedom, negative and positive, to ensure the proper range and character of freedom, then pointed out that Kant regarded freedom as a case within natural causality (in theoretical philosophy), to bypass if not repress the unique existence of human being. On the other hand, Kant restricted freedom to self-legislation of practical reason (in practical philosophy), to sever freedom from metaphysics. Finally, Heidegger insists that freedom should be in the metaphysical realm, not just in natural and moral realms. Heidegger thus proposed his own more broad view of freedom via critiques of Kant. Heidegger takes freedom as something ontological, more basic and comprehensive than what Kant envisaged.