The Keisei Main Line (京成本線, Keisei Honsen) is a railway line of Japanese private railway company Keisei Electric Railway connecting Tokyo and Narita, Japan. It is the main line of Keisei's railway network. Built as an interurban between Tokyo and Narita in the early 20th century, the line has served as a main access route to Narita International Airport since 1978. It also serves major cities along the line such as Funabashi, Narashino, and Sakura.

In 2010, the Narita Sky Access opened as a bypass of the line, reducing the role of the main line in the airport access.

All sections opened as electrified dual track unless noted otherwise. The initial section opened between Takasago and Edogawa as 1,372 mm (4 ft 6 in) gauge in 1912, and the line was progressively extended in both directions, reaching Narita in 1930 and Ueno in 1933.

In 1959, the line was regauged to 1,435 mm (4 ft 8+1⁄2 in). In 1978, it was extended to Narita Airport (now Higashi-Narita). The single track extension to Terminal 1 was opened in 1992.

There are numerous closed and abandoned stations listed in the route map above.

This article incorporates material from the corresponding article in the Japanese Wikipedia.