Production of lead silicate glass declined by 9th AD in Japan. Instead lead potash silicate glass (K2O-PbO-SiO2), a new compositional type of glass, flowed into Japan from China. Then lead potash silicate glass become a major glass type in the medieval period of Japan. Especially in Hokkaido, glass beads were favored by Ainu culture. So we focus on the circulation of glass in Hokkaido at the Ainu cultural period to understand the glass trade in relation with glass in Honshu. In this study, we analyzed glass beads excavated from sites in southern Hokkaido, which were important bases located between Honshu and central Hokkaido. The samples are excavated from archaeological sites at the periods from the 15th～19th century AD. The analytical results showed that these glass beads can be classified into two types – lead potash silicate glass (K2O-PbO-SiO2) and potash lime silicate glass (K2O-CaO-SiO2). These types of glass are also major types distributed in Hokkaido at the period of Ainu culture. In addition, we have found the presence of a large number of purple glass beads made of lead potash silicate glass utilizing antimony oxide as emulsifier. Interestingly, they are only characteristic to southern part of Hokkaido.