Ōamishirasato is a city located in Chiba Prefecture, Japan. As of 1 November 2020, the city had an estimated population of 49,019 in 21,860 households and a population density of 840 persons per km2. The total area of the city is 58.06 square kilometres (22.42 sq mi).

The Sotobō Line is a railway line in Japan operated by the East Japan Railway Company adjacent to the Pacific Ocean, on the eastern side of the Bōsō Peninsula. It connects Chiba Station in Chiba to Awa-Kamogawa Station in Kamogawa, passing through Ōamishirasato, Mobara, Chōsei, Ichinomiya, Isumi, Onjuku, and Katsuura. The line is connected to the Uchibō Line at both ends. South of Kazusa-Ichinomiya is single track, and north of Kazusa-Ichinomiya is double track.