Some controversial characteristics of postcolonial writing can be applied to James Joyce`s novel Ulysses. In the early twenties, the temporal background of the novel, Ireland was a colony of English imperialism, and Catholicism, as the mental prop of the Irish people, was gradually degraded. Although the Irish nationalism such as Sinn Fein tried to save the Irish people from this dismal situations, it became as violent as English Imperialism and also got very exclusive, narrow-minded, irrational and sentimental. As a result, in the matter of the Irish nationalism that first aroused his keen interest, Joyce later has taken a critical stance. Stephen Dedalus and Leopold Bloom in Ulysses go through cultural and psychological disruptions and are losing their identity as many Irish people do in this situation. This thesis examines how the Irish people are silenced and marginalized in the colonial society by focusing on some examples in "Telemachus", "Nestor" and "Circe". Thinking that Irish nationalism tends to become exclusive nationalism and cultural essentialism, Joyce is anxious about and warns against these corruptive aspects of Irish nationalism. Joyce in Ulysses attempts to indicate these negative aspects of Irish nationalism in the scene of Bloom`s defeating "The Citizen", the very chauvinistic character, in "Cyclops". The narrow-minded, exclusive and irrational character, "The Citizen", symbolizes the undesirable aspects of Irish nationalism but his logic of power is symbolically defeated by Bloom`s maintenance of love. This suggests that resisting the exploitation of English Imperialism by means of exclusive nationalism cannot but repeat colonial discourses based on binary oppositions. By showing the chauvinistic "The Citizen"s defeat by cosmopolitan Bloom, Joyce demonstrates that the exclusive nationalism and cultural essentialism cannot be effective means of resisting English imperialism. In conclusion, the desirable way of postcolonialism, as Joyce shows, is not so much resisting powerful dominance of English imperialism by means of power as overcoming colonial/dichotomous discourses groping for diverse ways of coexistence between nations beyond racial and political differences.