The Uchibō Line is a railway line operated by the East Japan Railway Company adjacent to Tokyo Bay, paralleling the western shore of the Bōsō Peninsula. It connects Soga Station in the city of Chiba to Awa-Kamogawa Station in the city of Kamogawa, passing through the municipalities of Chiba, Ichihara, Sodegaura, Kisarazu, Kimitsu, Futtsu, Kyonan, Tateyama, and Minamibōsō. The line is connected at both ends to the Sotobō Line. The name of the Uchibō Line in the Japanese language is formed from two kanji characters. The first, 内, means "inner" and the second, 房 is the first character of the Bōsō. The name of the line thus refers to its location along the inner part of the Bōsō Peninsula in relation to the Tokyo Metropolitan Area, as opposed to the Sotobō Line, "outer Bōsō" which is on the opposite side of the peninsula. South of Kimitsu is single track, and north of Kimitsu is double track.

The East Japan Railway Company is a major passenger railway company in Japan, the largest of the seven Japan Railways Group companies. The company name is officially abbreviated as JR-EAST or JR East in English, and as JR Higashi-Nihon in Japanese. The company's headquarters are in Yoyogi, Shibuya, Tokyo, next to Shinjuku Station. It is listed in the Tokyo Stock Exchange, is a constituent of the TOPIX Large70 index, and is one of three Japan Railways Group constituents of the Nikkei 225 index, the others being JR Central and JR West.