Chiyoda Line

The line has its origins in a 1962 report by the government’s Council for Urban Transport, which proposed a route running between the Kitami area in the southwest and the Matsudo direction in the northeast and designated it Tokyo Line 8. Later that year, in August 1962, a Ministry of Construction notice renumbered this route as Tokyo Line 9, because the line that had by then been settled as Line 8 became the present Yūrakuchō Line. Revisions in 1964 fixed the route’s through-running connections — to the Jōban Line at the northeastern end and to the Odakyū Odawara Line at the southwestern end — and on 16 December 1964 the project was confirmed as City Planning Line 9, a 32.5 km route between Kitami and Ayase.

The Eidan (Teito Rapid Transit Authority) formally decided to build the Ayase–Yoyogi-Uehara line in April 1964, and construction of the first stretch, between Kita-Senju and Ōtemachi, began on 30 July 1966. The route was given the name “Chiyoda Line” in September 1969, and the first section, Kita-Senju–Ōtemachi (9.9 km), opened on 20 December 1969; the opening pushed the Eidan’s total route length past 100 km. Trains at first ran as three-car sets of 5000 series stock, the new 6000 series then still being in test running. Capacity grew quickly: the trains were lengthened to five cars in December 1970, and when the Ōtemachi–Kasumigaseki segment (2.2 km) opened on 20 March 1971 the 6000 series entered revenue service and ten-car operation began.

Through-running, which would come to define the line, began at the northeastern end on 20 April 1971, when the Ayase–Kita-Senju segment (2.6 km) opened and reciprocal through-services started with the Japanese National Railways (JNR) Jōban local line as far as Abiko; the Ayase–Kita-Senju section thereby became a stretch shared with the Jōban Line for fare purposes. The Kasumigaseki–Yoyogi-Kōen segment (6.2 km) followed on 20 October 1972. The last and most delayed stretch, Yoyogi-Kōen–Yoyogi-Uehara (1.0 km), opened on 31 March 1978, completing the line; on the same day reciprocal through-running began with the Odakyū Odawara Line as far as Hon-Atsugi, at first only on weekday mornings and evenings and running as a semi-express within the Odakyū line.

A short branch from Ayase to Kita-Ayase (2.1 km) opened on 20 December 1979, converting what had been a depot access line to passenger use. The Jōban through-service was extended in the peak hours to Toride on 15 November 1982, served by new 203 series trains. When JNR was divided and privatised on 1 April 1987, the line’s through-running partner at the eastern end became the East Japan Railway Company (JR East). On 1 April 2004 the Eidan itself was corporatised, and the Chiyoda Line, like the rest of the former Eidan network, passed to the newly created Tokyo Metro Co., Ltd.

On 20 March 1995 the Chiyoda Line was one of the lines struck in the Tokyo subway sarin attack. In the years that followed the line saw a steady programme of upgrades, including a switch to new CS-ATC signalling across the whole line in 1999 and the introduction of women-only cars in the morning peak from 15 May 2006. A landmark in the through-services came on 15 March 2008, when Odakyū’s reserved-seat Romancecar limited expresses (the 60000 series “MSE”) began running through onto the Chiyoda Line — the first regular reserved-seating limited-express service to operate over a Japanese subway line.

More recent changes have continued to reshape the line’s rolling stock and through-services. The 16000 series entered service in November 2010, and the original 6000 series was retired on 11 November 2018 after nearly half a century. On 16 March 2019 the platform at Kita-Ayase was lengthened to take ten-car trains and through-services began between Yoyogi-Uehara and Kita-Ayase, upgrading the former shuttle branch. Through-running with the Odakyū Tama Line was discontinued in March 2022 and then reinstated in March 2025. Today the Chiyoda Line remains a green-coded central artery of the Tokyo Metro network, threading from the Odakyū suburbs in the west, across the heart of Tokyo, and out onto the Jōban corridor in the northeast.

• 1962A Council for Urban Transport report proposes the route (Kitami–Matsudo direction) as Tokyo Line 8; a Ministry of Construction notice in August renumbers it Tokyo Line 9.
• 196416 December: the project is confirmed as City Planning Line 9, a 32.5 km Kitami–Ayase route, with through-running connections fixed to the Jōban Line and the Odakyū Odawara Line.
• 196630 July: construction of the first section, Kita-Senju–Ōtemachi, begins.
• 196920 December: the first section, Kita-Senju–Ōtemachi (9.9 km), opens (named the “Chiyoda Line” that September); the opening pushes the Eidan’s total route length past 100 km. Trains run as three-car 5000 series sets.
• 197120 March: Ōtemachi–Kasumigaseki (2.2 km) opens, the 6000 series enters service and ten-car operation begins. 20 April: Ayase–Kita-Senju (2.6 km) opens and through-running starts with the JNR Jōban local line to Abiko.
• 197220 October: Kasumigaseki–Yoyogi-Kōen (6.2 km) opens.
• 197831 March: the final segment, Yoyogi-Kōen–Yoyogi-Uehara (1.0 km), opens, completing the line; reciprocal through-running with the Odakyū Odawara Line to Hon-Atsugi begins the same day.
• 197920 December: the Ayase–Kita-Ayase branch (2.1 km) opens, converting a depot access line to passenger use.
• 198215 November: Jōban through-running is extended to Toride in the morning and evening peaks; new 203 series trains enter service.
• 19871 April: with the division and privatisation of JNR, the line’s eastern through-running partner becomes JR East.
• 199520 March: the Chiyoda Line is one of the lines struck in the Tokyo subway sarin attack.
• 20041 April: the Eidan is corporatised and the Chiyoda Line passes to the newly created Tokyo Metro Co., Ltd.
• 200615 May: women-only cars are introduced on the morning peak.
• 200815 March: Odakyū’s reserved-seat Romancecar limited expresses (60000 series “MSE”) begin through-running onto the Chiyoda Line — the first regular reserved-seating limited express to run over a Japanese subway line.
• 201811 November: the original 6000 series is retired after nearly half a century in service.
• 201916 March: the Kita-Ayase platform is lengthened for ten-car trains and through-running begins between Yoyogi-Uehara and Kita-Ayase.