This paper treats of the underground stratigraphy of the Pleistocene Saijo lacustrine Formation in the urban area of the city of Higashi-Hiroshima in Hiroshima Prefecture，western Japan. The Saijo lacustrine Formation is developed in the areas of Higashi-Hiroshima City (N.L.34°25' ; E.L.132°44')，Kurose，Kumano，Gohara (N.L.34°25' ; E.L.132°38') in the southern part of Kamo-highland in Hiroshima Prefecture. This formation was studied by many geologists such as Hashimoto et al. (1958)，Kokawa (1962)，Tai (1964)，Kakitani et al. (1976)，Fukuhara (1977)，Higashimoto et al. (1985)，Mizuno et al. (1986)，Mizuno et al. (1993)，Miyoshi et al. (1994)，Sada et al. (1996)，and Takehara et al. (1999). However，many problems still remain unsolved. We studied the underground stratigraphy of Saijo，the urban area of the city of Higashi-Hiroshima and identified the Saijo lacustrine Formation overlying unconformably the basement rock of Hiroshima granite. This formation is not more than 10 m in thickness. Hereafter，we will try to collect more columnar sections which were gained by drilling bore hall，and pursue the study of the underground stratigraphy of this formation in this area.