In North-Eastern Asia, the Pan-mixed forest zone was characterized as an ecotone between temperate and boreal zone of East Asia by Tatewaki (1958), including main part of Hokkaido, South Sakhalin, South Kuril, Amur, Primorye, Northeast China, and North Korea. In this ecotone, floristical compositions of distribution pattern were classified in order to clarify the phytogeographical relationships between Japan and Fareast Russia, especially it was based on the common species in the floras of Primorye and Japan. Among ca. 1070 common species, ca. 400 species belong to the Northeast China(Manchuria)-Korea element, including the Honshu-Kyushu-Korea type (ca. 150 species), the Hokkaido-Honshu-Kyushu-Korea type (ca. 150 species), and the East Siberia-Sakhalin-Hokkaido-Honshu-Kyushu-Korea type (ca. 100 species). As the result it suggests that many species of Hokkaido might be originated from Korean Peninsula rather than Sakhalin. On the other hand, the East Siberia-Sakhalin- Hokkaido-Central Honshu type (ca. 70 species) and other northern elements such as circumpolar element, North Pacific element, Northeast Asian element, etc.(ca. 360 species) suggest the distributional route to Japan via Sakhalin. Furthermore, flora of Primorye has the other southern elements (ca. 240 species).