Rousseau's "Democratic Republicanism" and Kant's "Constitutional Republicanism" are two important albeit conflicting paradigms of the transition from classical to contemporary Republicanism. In this paper, we aim to analyze the differences between Republican Ideal and Political Innovation. At first, we compare the differences in the Republican Ideals of Rousseau and Kant by proposing two different schemes of ideas: Rousseau's "autonomous freedom- general will-sovereignty-laws-republic" and Kant's "autonomous freedom- principle of right-public will-the state in idea-republic". Secondly, we analyze the two different discourses of Political Innovation in order to explain how they create a "republic" and maintain their own existence in a limited spacetime (temporal finitude). In conclusion, through the above comparison of the Republican Ideal and Political Innovation, we try to clarify the differences between these two paradigms while indicating their distinctive meaning in terms of relevance of contemporary republicanism.