This article attempts to discuss Fitzgerald`s frequent use of oxymoron in The Great Gatsby. Oxymoron is a representative figure of speech in the novel and closely related to its thematic concerns. The significant ironies and paradoxes are represented and reinforced by oxymorons throughout the novel. First of all, most of the main characters Nick introduces are described as a combination of two contradictory or opposite words, reflecting their positive and negative attributes. Such a doubleness of each characterization represents the struggling of right and wrong, good and bad, east and west, idealism and materialism in America`s 1920s. Especially, Gatsby`s doubleness is related to his criminal corruption of materialism fronting his romantic “incorruptible dream” of idealism. As a majority of people in the 1920`s America pursued the Dream of Success, most of the characters in the novel are caught up in a world of wealth, but they don`t end up getting what they want with money. In conclusion, oxymoron is effectively used to prove the doubleness of the characters, especially in Gatsby`s dream toward Daisy, and the contradictions of the Dream of Success in 1920`s America.