By focusing on the poetic way in which Walt Whitman in Leaves of Grass envisions the ideal harmony of democracy and individualism by means of incorporating the two ideologies into a cosmopolitan vision, this essay examines how it ironically proves their essential, constitutive incompatibility. For Whitman who desires to make himself the bard of American democracy, I argue, free and equal individuals are the important foundational ground for celebrating the American values and ideals of democracy and individualism. However, democracy and individualism, though they seem to share the same conceptual principles, are in effect incompatible due to their irreconcilable ideological antagonism, which Whitman comes to recognize and attempts to overcome by way of offering a series of imaginary depictions of a cosmopolitan world in which free and equal individuals can travel facing no hostility in other regions or countries. Whitman suggests such Kantian cosmopolitanism in the future tense as a sole solution to the unbridgeable gap between democracy and individualism, which however indicates ironically its substantial impossibility in the present tense.