Korean medical journals were continuously published during the period of Japanese colonization of Korea. Various advertisements by herbal drugs manufacturers were in these journals, targeting Korean medical doctors or students who aspired to be Korean medical doctors. The advertisements varied from small ones to large-scale ads. At first these advertisements covered only dried herbs, but with time, they came to advertise various kinds of drugs. Advertisement of merchandise drugs brought many changes to the medical culture of Korea. Korean medical doctors who only prescribed dried herbs before began to prescribe merchandise drugs as well. When treating patients, they not only used Korean drugs but also actively prescribed merchandise drugs and western drugs, showing an advancement in treatment. As Korean medical doctors played the role of providers of merchandise drugs, herbal drugs manufacturers and Korean medical doctors seemed as sellers and consumers on the surface. However, they maintained a relationship where Korean medicine worked as the common denominator. Among merchandise drugs, Yoeng-so-hwan, Bi-jeon-go, and Myeol-dok-hwan were advertised often, and this shows that people at the time suffered mostly from digestive diseases, skin diseases, and sexually transmitted diseases. Herbal drugs manufacturers were business managers whose main objective was to make a good profit, but they consisted a part of Korean medical society. Like Korean medical doctors, they were anxious about the fall of Korean medicine. As a part of popularization of Korean medicine, they encouraged Korean medical doctors to treat patients using herbal drugs and merchandise drugs. This thought was reflected well in advertisements and Korean medical doctors made use of this thought well.