The emergence of modern health-related commodities and tourism in the late Meiji and Taishō eras (1900s–1920s) was accompanied by a revival of spiritualist religions, many of which had their origins in folk belief. What helped this was the people’s interpretation of radiation. This article underscores the linkages between radiation, science and spiritualism in Japan at the time of modernisation and imperialism. In the early twentieth century, the general public came to know about radiation because it was deemed to have special efficacy in healing the human body. In Japan, the concept of radiation harmonised with both Western culture and Japanese traditional culture. One can see the fusion of Western and traditional culture both in people’s lives and commercial culture through the popularity and availability of radium hot springs and radioactive commodities. Radium hot springs became fashionable in Japan in the 1910s. As scholars reported that radium provided the real potency of hot springs, local hot springs villages seized on the scientific explanation and connected their developments with national policies and industries. This paper illustrates how the discourse about radium, which came from the field of radiation medicine, connected science and spiritualism in modern Japan.