|Locale||Tokyo, Kanagawa prefectures|
|Stations||26 (main line), 3 (branch line)|
|Rolling stock||205-1000 series, E233-8000 series, E233-8500 series|
|Daily ridership||840,241 (daily 2015)|
|Line length||45.0 km (28.0 mi)|
|Track gauge||1,067 mm (3 ft 6 in)|
|Electrification||1,500 V DC overhead catenary|
The Nambu Line (Japanese: 南武線,Japanese pronunciation: [Nanbu-sen]) is a Japanese railway line which connects Tachikawa Station in Tachikawa, Tokyo and Kawasaki Station in Kawasaki, Kanagawa. For most of its length, it parallels the Tama River, the natural border between Tokyo and Kanagawa prefectures. It lies along the Tama Hills. It is part of the East Japan Railway Company (JR East) network. The line forms part of what JR East refers to as the "Tokyo Mega Loop" (Japanese: 東京メガループ) around Tokyo, consisting of the Keiyo Line, Musashino Line, Nambu Line, and the Yokohama Line. The name refers to the southern (Japanese: 南) part of the ancient province of Musashi (Japanese: 武蔵) (now Tokyo and northern Kanagawa prefecture), through which the Nambu Line runs.
"Rapid" service trains (two trains per hour between 10 a.m. and 4 p.m) do not stop at Shitte, Yakō, Hirama, Mukaigawara, Tsudayama, Kuji, Shukugawara, Nakanoshima, Yanokuchi, Minami-Tama, Nishifu, Yaho, Yagawa, or Nishi-Kunitachi. All other trains except for some seasonal services are "Local" services, stopping at all stations.
|Kawasaki||川崎||-||0.0||●||Tōkaidō Main Line, Keihin-Tōhoku Line
Keikyu Main Line, Keikyu Daishi Line (Keikyū Kawasaki)
|Shitte||尻手||1.7||1.7||｜||Nambu Branch Line (for Hama-Kawasaki)||Saiwai-ku, Kawasaki|
|Kashimada||鹿島田||1.5||4.1||●||Yokosuka Line, Shonan-Shinjuku Line (Shin-Kawasaki).||Saiwai-ku, Kawasaki|
|Musashi-Kosugi||武蔵小杉||0.9||7.5||●||Yokosuka Line, Shōnan-Shinjuku Line|
Tokyu Toyoko Line, Tokyu Meguro Line
|Musashi-Mizonokuchi||武蔵溝ノ口||2.2||12.7||●||Tokyu Den-en-toshi Line, Tokyu Oimachi Line (Mizonokuchi)||Takatsu-ku, Kawasaki|
|Noborito||登戸||1.1||17.3||●||Odakyu Odawara Line|
|Inadazutsumi||稲田堤||1.3||20.8||●||Keio Sagamihara Line (Keiō-Inadazutsumi)|
|Minami-Tama||南多摩||1.4||25.5||｜||Seibu Tamagawa Line (Koremasa)|
|Tachikawa||立川||1.2||35.5||●||Chūō Main Line, Ōme Line|
Tama Toshi Monorail Line (Tachikawa-Kita, Tachikawa-Minami)
|Shitte||尻手||-||0.0||Nambu Line (main line), Nambu Line (freight branch)||Saiwai-ku, Kawasaki|
|Hatchōnawate||八丁畷||1.1||1.1||Keikyu Main Line
Tokaido Main Line freight branch (for Tsurumi)
|Hama-Kawasaki||浜川崎||1.4||4.1||Tsurumi Line, Tokaido Main Line freight branch (for Kawasaki Freight Terminal)|
The "Shitte crossover" (尻手短絡線, Shitte-tanraku-sen) connects Shitte Station and Shin-Tsurumi Yard on the Tōkaidō Main Line (Hinkaku Line) and the Musashino Line. Freight trains operating between Tokyo Freight Terminal and northern Japan operate on both branch lines.
As of 1 October 2016[update] the following fleet of electric multiple unit (EMU) trains is used on Nambu Line services, with all trainsets based at Nakahara Depot.
From 15 March 2017, the last remaining 209 series trainset, set 53, was replaced by a six-car Ome Line and Itsukaichi Line E233-0 series set 670 modified and renumbered to become E233-8500 series set N36.
The private Nambu Railway opened the line in five stages between 1927 and 1930 (freight branches are omitted):
Passenger trains utilised electric multiple units (EMUs) from the beginning. Freight initially consisted primarily of gravel hauled from the Tama River. When the railway reached Tachikawa and made connection with the Ōme Electric Railway, limestone became one of the main freight commodities. The railway was controlled by Asano zaibatsu, which enabled the transport of limestone from its own quarry in Western Tokyo to its cement plant in Kawasaki without using the government railways.
On April 1, 1944, the railway was nationalised by the imperial government and became the Nambu Line of Japanese Government Railways. After the end of World War II, there were several calls for the privatisation of the line, but the line remained a part of the Japanese National Railways (JNR) until its privatization in 1987.
The postwar growth of the Tokyo urban area resulted in the conversion of most of the farmlands along the Nambu Line into residential areas and increased the passenger traffic on the line. Freight traffic reduced after the opening of the Musashino Line (parallel to the Nambu Line) in 1976 and the discontinuance of the limestone freight in 1998, except for the Nambu Branchline, which remains a major freight route.
Limited-stop "Rapid" services between Kawasaki and Noborito with stops at Musashi-Kosugi and Musashi-Mizonokuchi started on December 15, 1969, but were discontinued by the timetable revision on October 2, 1978. After 33 years, Rapid services between Kawasaki and Tachikawa with more stops started on April 9, 2011, postponed from the originally scheduled March 12 due to the 2011 Tōhoku earthquake and tsunami.