The dissertation made use of “Taiwan kuan Hsi Chi Shih,” (Taiwan Etiquette and Custom Note) “Min Su Taiwan,” (Taiwan Folk Custom) and partial relevant writings of government employees to explore the continuous situation of traditional Taiwanese Han people’s illness-treating behaviors during the Japanese Colonial Period, and attempted to probe into the colonial government’s attitude for superstition and ways of treating it in the meantime. It was found that in the initial stage of ruling Taiwan, mostly the Japanese people used a scientific and empirical angle to define whether Taiwanese traditional folk custom and belief were superstitions or not; in the later stage, in order to pursue the assimilation with Japan, superstition was imposed on most of Taiwanese traditional customs by the Japanese people. However, the formation of tradition has its own deep cultural factors which can not be completely changed via the country’s law or educational means. Even though experiencing the Japanese colonial period and post-war modernization, part of the tradition of the ways of medical treatment applied by Taiwanese Han people in the period of pre-modern times was still deep-rooted in common people’s life.