The Sasagami hills located to the east of the Niigata plain are one of the most suitable area for the study of the Shibata-Koide tectonic line (Yamashita, 1970). The movement of this tectonic line since Miocene is closely related to the tectonic development of the Niigata Cenozoic sedimentary basin. In addition in this area, it was said that the Pleistocene strata correlative to the "Yashiroda Formation", which gives rise to some problems in relation to the standard stratigraphy of Niigata prefecture, are widely distributed. In this paper, the present writer intends to describe the detailed stratigraphy of the Miocene to the Pleistocene strata especially of the "Yashiroda Formation", and to restore the movement of the Shibata-Koide tectonic line. Results of the research are summarized as follows: 1. On the east side of the Shibata-Koide tectonic line, the Miocene series are divided into the Arakawa Formation and the Yamanokami Formation, which unconformably overlies the granitic basement of the Gozu mountains. 2. On the west side of the tectonic line, the continuous deposits from the Miocene to the Pleistocene are distributed on the Sasagami hills. They are classified into the Sakanaiwa, the Haguro, the Dainich, the Sasagami Formations, the Zingamine conglomerate member and terrace deposits. 3. Based on the lithologic facies and the fossils yielded, the Sasagami Formation can be correlated to the Uonuma Group and not to the "Yashiroda Formation". 4. Well developed terraces on the west and the south of the Sasagami hills are divided into the following three groups from their relative height: T1 group (20〜30m in relative height), T2 group (1〜15m) and T3 group (0〜2m). 5. The Shibata-Koide tectonic line in this area may be represented by a step-fault system with westerly throwndown sense. The total throw is estimated more than 4000 m. 6. The notable appearance of the Shibata-Koide tectonic line might be in the late Miocne to the Pliocene, and the particular topography in the Gozu-Sasagami area would be formed since the middle Pleistocene.

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