The primary objective of An Inquiry into the Nature of Aesthetic Theory in Its Relation to Theory of Knowledge in Kant's Critical Philosophy is to investigate Kant's aesthetic theory and its problematic relation to theory of knowledge in his transcendental philosophy. In the Critique of Judgment, Kant constructs his aesthetic theory by arguing that the aesthetic experience is based on a certain type of feeling, namely, the feeling of pleasure, rather than a concept. He grounds such a feeling on the aesthetic judgment of reflection. In spite of its nonconceptual and subjective characteristic, an aesthetic reflective judgment still has a claim to be universally valid. Here, the feeling of pleasure in beautiful is produced by the free harmonious relation between the imagination and the understanding. Judgment, in its reflective employment, does not determine its object but determines the feeling of pleasure in the judging subject. On the other hand, the categories, as pure concepts of the understanding, carry nearly all the weight in his theory of knowledge presented in the Critique of Pure Reason. The imagination, in this case, is strictly bound up by the rules that are imposed by the concepts of the understanding. By this way, judgment, as a cognitive faculty, determines its object and gains its objective validity. In this context, this book discusses the nature of Kant's aesthetic theory and the components that constitute a pure aesthetic judgment of reflection and attempts to clarify its proper place in critical philosophy regarding his theory of knowledge.