The JR Keiyō Line (京葉線) is a railroad that connects Tokyo Station in Tokyo, Japan and Soga Station in the city of Chiba, in Chiba Prefecture. Measuring 43.0 km in length, the Keiyo Line is a narrow gauge (1067 mm) passenger line of the East Japan Railway Company. It serves visitors to Tokyo Disney Resort and the Makuhari Messe exhibition center as well as commuters.

The terminus at Tokyo Station is located underground some distance to the south of the main station complex about half way to Yurakuchō Station. This means transfer between other lines at Tokyo Station can take between 15 and 20 minutes.

Part of the line opened in 1986, and the line became complete in 1990.

The name Keiyō is derived from the composition of the second characters of the names the cities linked by the line, Tōkyō (東京) and Chiba (千葉).

The Keiyō Line should not be confused with the Keiō Line of the private Keiō Electric Railway (京王線), whose terminus is at Shinjuku.