There is no doubt that the colonial period was a critical time for the establishment and expansion of modern Western medicine in Korea. However, did this act as a catalyst for the overall decline of traditional Korean medicine? While previous studies mainly focus on research based on the concept of Uisaeng (traditional Korean medicine doctor) and the medical policies implemented by the Japanese Government-General of Korea, this paper begins with the Korean herbal medicine industry, and comprehensively investigates the distribution and consumption of Korean herbal medicines during the colonial period from three perspectives: the policies for Korean medicine merchants implemented by the Japanese Government-General of Korea, changes in the Korean herbal medicine industry, and consumption of Korean herbal medicines in the Korean society. The colonial authorities' intention was to foster the advancement of Western medicine and phase out traditional Korean medicine. However, they merely imposed limitations on Uisaengs' operations-this policy loophole objectively left a window for Korean medicine merchants. Moreover, against the backdrop of the growing popularity of Western medicine and restrictions on the development of traditional Korean medicine by colonial authorities, the Korean herbal medicine industry, as one of the few "national industries" dominated by and serving Koreans, showed its tenacious vitality during that time. Korean medicine merchants responded to market changes with ease. They built different drugstores, such as traditional herbal stores mainly selling traditional Korean medicines, hybrid drugstores that simultaneously dealt with the manufacture and sale of patent medicines, and ginseng drugstores that specialized in the ginseng business. This classification promoted the commercialization of traditional Korean herbal medicine. Another crucial condition for the vitality of the Korean herbal medicine industry is Koreans' preference for traditional Korean medicine. It is an indisputable fact that Western medicine gradually became popular and was recognized by the common man during the colonial period; nonetheless, Eastern medicine and Western medicine were not playing a zero-sum game. Through comprehensive macro and micro analysis, this paper demonstrates that, during the colonial period, when old and new ideas interacted, most Koreans, including upper-class elites and intellectuals who were open-minded about emerging concepts and options and had ample opportunities to avail western medical treatment, preferred traditional Korean medicine. Using Korean herbal medicines for illnesses remained the primary choice, While Western medicine assumed the role of a supplement to traditional treatment. This paper argues that the first reason for this phenomenon is the inertia of tradition, and the second is that Western medicine was not necessarily more effective than Korean herbal medicine at that time. Specifically, it can be considered that, during the colonial period, the growing popularity of Western medicine failed to bring about a radical change in Koreans' regular medical interventions. Simultaneously, the Korean herbal medicine industry, one of the pillars offering medical support to the common man, adapted suitably while relying on the inertia of its own tradition. The industry's vitality and dynamism during the colonial period certainly underscore the need to amend the one-sided narrative of medical modernization vis-à-vis Western medicine.