The Hokusō Line is a commuter rail line operated by the third-sector Hokusō Railway in Japan. It runs between Keisei-Takasago Station in Katsushika, Tokyo and Inba-Nihon-Idai Station in Inzai, Chiba. It is part of the primary Keisei route between central Tokyo and Narita International Airport through the Narita Sky Access Line. It uses the ATS Type 1 system. The line's name is derived from its route through the former Shimōsa Province, which is also known as "Hokusō".

The Keisei Electric Railway Company, Ltd. is a major private railway in Chiba Prefecture and Tokyo, Japan. The name Keisei is the combination of the kanji 京 from Tokyo (東京)and 成 from Narita (成田), which the railway's main line connects. The combination uses different readings than the ones used in the city names. The railway's main line runs from Tokyo to Narita and the eastern suburb cities of Funabashi, Narashino, Yachiyo, and Sakura. Keisei runs an airport limited express train called the Skyliner from Ueno and Nippori to Narita International Airport.