The purpose of this work is to examine the rise of the value of social ethics in modern Japan. Around the time of the Meiji Restoration (1868), Japan started a momentous movement of learning from the West, which was named by its proponents as bummei kaika ("civilization and enlightenment"). In this conception, the West represents more than another people or socio-political realm; it stand also for a transcendent ideal-civilization. Emulating the West is to be civilized. The program of bummei kaika thus included reforms in moral values and social customs. As a result, the issue of social ethics appeared in the thought and education of modern Japan. NO clear notions of social ethics existed at the beginning of the Meiji era. Yet, related issues and norms already appeared. In the 1880s and 1890s, though scarce and poorly formulated, formal discussions of social morality came into being. During this period, kotoku (literally "public morality") was gradually adopted as a main concept representing the value of social ethics. At the turn of the twentieth century, particularly in 1901, came a major wave of expounding and promulgating the idea of kotoku. By all indications, this current successfully established social ethics as an important value in the Japanese consciousness, and this is no small change in the history of East Asian moral thought. At the end of this paper, the author uses the case of social ethics to illustrate the different features of cultural change in modern china and Japan.