Tsushima was an important point in ancient trade between Japan and the Eurasian Continent. Many Korean artifacts have been excavated from Tsushima by archaeological investigations. The purpose of our study is to reveal the chemical compositions of ancient glass excavated from Tsushima and the ancient glass trade between Japan and the Eurasian Continent. In this study, 127 ancient glass beads from Kofunosae site (Kofun period) and Kagarimatsubana site (Yayoi period) were nondestructively analyzed by using portable XRF (X-ray fluorescence) spectrometer. The chemical compositions of glass beads from two sites can be classified into three types: potash silica glass (K2O-SiO2), soda lime silica glass (Na2O-CaO-SiO2), high alumina soda lime silica glass (Na2O-Al2O3-CaO-SiO2). The glass beads excavated from Kofunosae site were classified into these three glass types. The results show that the number of alumina soda lime silica glasses is largest in the glass samples excavated from the sites. On the other hand, the glass beads excavated from Kagarimatsubana site are all potash silica glass. Moreover, we revealed that 13 colorless glass beads from Kagarimatsubana site don’t conclude any colorants. Such glass beads are rarely found in Japan.We were able to reveal the chemical characteristics of ancient glasses excavated from Tsushima and a part of glass trade between Japan and the Eurasian Continent based on on-site non-destructive XRF analyses.