The street trees are one of urban ecosystem where are exposed to unique environmental stresses for plants. In previous study of flora under street trees showed that species configuration from in seven European cities are homogeneous. To check whether the flora under street trees in Northeastern Asia shows similar trend or not, we investigated 145 and 76 street trees with 1,192 pictures containing GPS in Seoul, Korea and Tokyo, Japan in September 2017, respectively. We established the web-based database named as Street Tree Flora Database, which was developed based on Biodiversity Observation Database. 62 species were identified (44 species in Seoul and 40 species in Tokyo, 22 species overlapped) belonging to 22 families. Asteraceae was the biggest family, followed by Poaceae in both cities. Number of species per each street tree in Seoul(4.82) and Tokyo(15.78) are quite different. Only 9 of 62 species in NE Asia were overlapped with 29 common species in Europe, indicating that species composition in both continents can be different. Street tree Flora Database for analyzing collected data will be a basic resource for understanding detailed flora of urban area in several countries.