The setting of the book The Christ of Nanjing is the semi-colonization of China by Japan in the 1920s. This book reflected the understanding of Chinese society and criticism of colonialism by Ryonosuke Akutagawa; however, a review of this work shows it to be insufficient for a thorough criticism of colonialism. My research started with the metaphor of syphilis that was featured in The Christ of Nanjing. After learning that syphilis was transmitted from the American continent to Europe during the European colonization and domination of the Americas after Columbus's voyage, Akutagawa consciously defined the disease transmitted from a Chinese woman to a mixed-heritage Japanese-Americans as syphilis. From this point, the thought can be distinctly inferred that Akutagawa regarded the opposing relationship between China and Japan as the relationship between a dominated state and an empire. Moreover, syphilis, which resulted in madness in those of mixed-heritage was a metaphor for danger from the dominated China, which had not been realized by imperialist states. Nevertheless, the book's traveler from Japan who contacted the Chinese prostitute Jinhua Song was not infected with syphilis like those of mixed heritage. In view of this, the Japanese traveler represented only Japan while the mixed-heritage JapaneseAmerican represented westernized Japan. Akutagawa may have found a new way to treat colonialism according to the way the Japanese traveler behaved with Jinhua Song. He simulated and criticized the colonization policy, thought that it would destroy Chinese civilization, and that Chinese people might resist. However, Akutagawa only raised doubts about the appropriateness of colonization but did not condemn colonialism. This explains the lack of thoroughness of its criticism of colonization.