Токио қалалық айналма темір жол желісі

Railway loop line in Tokyo, Japan

The Yamanote Line (山手線) is a loop service in Tokyo, Japan, operated by the East Japan Railway Company (JR East). It is one of Tokyo's busiest and most important lines, connecting most of Tokyo's major stations and urban centres, including Marunouchi, the Yūrakuchō/Ginza area, Shinagawa, Shibuya, Shinjuku, Ikebukuro, and Ueno, with all but two of its 30 stations connecting to other railway or underground (subway) lines. Internally JR East refers to the "Yamanote Line" as the quadruple track corridor between Shinagawa and Tabata via Shinjuku. The corridor consists of a pair of tracks used by Yamanote local trains and another parallel pair of tracks called "the Yamanote Freight Line" used by the Saikyō and Shōnan Shinjuku line trains, some limited express services, and freight trains. In everyday usage, branding on maps and station signage, the "Yamanote Line" refers to the local service (also called "system") running the entire line looping between the Yamanote corridor via Shinjuku Station and the central portions of the Tōhoku and Tōkaidō Main Lines Via Tokyo Station. (This article uses the same definition unless noted otherwise.)

Trains run from 04:26 to 01:04 the next day at intervals as short as 2 minutes during peak periods and four minutes at other times. A complete loop takes 59 to 65 minutes. All trains stop at each station. Trains are put into and taken out of service at (which for timetabling purposes is the line's start and terminus) and sometimes Certain trains also start from Tamachi in the mornings and end at in the evenings. Trains which run clockwise are known as sotomawari (外回り) and those counter clockwise as uchi mawari (内回り). (Trains travel on the left in Japan, as with road traffic.) The line also acts as a fare zone destination for JR tickets from locations outside Tokyo, permitting travel to any JR station on or within the loop. This refers to stations on the Yamanote Line as well as the Chūō Sōbu and Chūō Rapid Lines and between and
The Yamanote Line colour used on all rolling stock, station signs and diagrams is JNR Yellow Green No.6 (■, Munsell code 7.5GY 6.5/7.8), known in Japanese as Japanese bush warbler (ウグイス色).

Due to the Yamanote Line's central location connecting most of Tokyo's major commuter hubs and commercial areas, the line is very heavily used. Sections of the line were running over 250% capacity in the 1990s, remained above 200% for most of the 2000s with most sections dropping below 150% in 2018. This is due to larger and more frequent trains being introduced to the Yamanote Line and the opening of parallel relief lines such as the Tokyo Metro and Ueno–Tokyo Line. The maximum overcrowding during rush hour is about 158%. The ridership intensity of the Yamanote Line in 2018 was 1,134,963 passengers km / km of route. However, in both cases "Yamanote Line" refers to JR East's internal definition of the entire rail corridor between Shinagawa and Tabata stations via Shinjuku which includes the ridership of the Saikyō and Shōnan–Shinjuku Lines on the parallel Yamanote freight line. Meanwhile, the ridership of the Yamanote Line services between Tabata and Shinagawa Station via Tokyo are excluded and counted as part of the Tōhoku and Tōkaidō Main Lines.

"Yamanote" literally refers to inland, hillier districts or foothills (as distinct from areas close to the sea). In Tokyo, "Yamanote" lies along the western side of the Yamanote Line loop. The word consists of the Japanese morphemes yama, meaning 'mountain', the genitive suffix no, and te, meaning 'hand', thus literally translating as "mountain's hand", analogous to the English term "foothills". Yamanote sen is officially written in Japanese without the kana no (の、ノ), which makes its pronunciation ambiguous in print. The characters may also be pronounced yamate, as in Yamate dōri (Yamate Street), which runs parallel to the west side of the Yamanote Line. The Seishin Yamate Line in Kobe and the Yamate area of Yokohama also use this pronunciation. After World War II, SCAP ordered all train placards to be romanized, and the Yamanote Line was romanized as "Yamate Line". It was thus alternatively known as "Yamanote" and "Yamate" until 1971, when the Japanese National Railways changed the pronunciation back to "Yamanote". Some older people still refer to the line as the "Yamate Line".

The predecessor of the present day Yamanote Line was opened on 1 March 1885 by the Nippon Railway Company, operating between Shinagawa Station in the south and Akabane Station in the north. The top part of the loop between and (a distance of ) opened on 1 April 1903, and both lines were merged to become the Yamanote Line on 12 October 1909. A parallel freight line, also completed in 1925, ran along the inner side of the loop between Shinagawa and Tabata. During the prewar era, the Ministry of Railways did not issue permits to private suburban railway companies for new lines to cross the Yamanote Line from their terminal stations to the central districts of Tokyo, forcing the companies to terminate services at stations on the line. This policy led to the development of new urban centers (新都心、副都心) around major transfer points on the Yamanote Line, most notably at and (which are now the two busiest passenger railway stations in the world). The contemporary Yamanote Line came into being on 19 November 1956 when it was separated from the Keihin Tōhoku Line and given its own set of tracks along the eastern side of the loop between Shinagawa and
A new station, Takanawa Gateway Station, opened on 14 March 2020. This station was built on the Yamanote Line and Keihin Tohoku Line between Shinagawa and Tamachi stations, becoming the first new station on the line since Nishi Nippori was built in 1971. The distance between Shinagawa and Tamachi stations was , making it the longest stretch of track between stations on the Yamanote Line.