The present study sheds light on the structural aspect of disease and death in colonial Korea by examining the whole picture of the Spanish influenza, which was pandemic during 1918-1921, and exploring its socioeconomic effects. The Spanish influenza likewise emerged in colonial Korea through the process of presymptoms in spring, with the first epidemic characterized by high morbidity rates and low death rates, and the second epidemic characterized by low morbidity rates and high death rates. Consequently, nearly half of the population fell ill, over 200,000 from among them losing their lives. While the morbidity rate per ethnic group was similar for ethnic Koreans and Japanese or higher for the latter group, the fatality rates revealed salient disparities. Indeed, the structure of disease and death where the Japanese showed low death rates, which surfaced throughout the colonial period, emerged in this case, too. Regarding the pandemic of the influenza, the Government-General of Korea (GGK), the Japanese colonial ruling organ, devised measures through the police hygiene system but failed to be effective. As a result, not only did many inevitably lose their lives but also the socioeconomic effects were considerable, including a drastic rise in rice prices and the temporary closures of schools and offices. This led to discontent with the colonial ruling system and to the March 1 Independence Movement, as a result of which Japan’s colonial policy changed into one based on “culture” and “development.” In the process, demographic transitions such as a decrease in the death rates appeared during the 1920s.