Sapporo Municipal Subway Tozai Line

Planning for an east–west subway dates to the 1960s, when the city drew up a high-speed transit construction programme. On 4 October 1971 the Sapporo city assembly approved construction of the first section, between Kotoni and Shiroishi. The municipality obtained a local-railway construction licence for that section on 18 May 1972, held a groundbreaking ceremony on 29 March 1973, and began work on 18 May 1973. With the central segment under way, the assembly went on to approve the eastward extension from Shiroishi to Shin-Sapporo on 24 February 1975.

The Tōzai Line opened on 10 June 1976 between Kotoni and Shiroishi, a distance of 9.9 km. From the outset it was operated automatically, using Automatic Train Operation, with a fleet of four-car 6000 series trains (twenty sets, eighty cars). At Ōdōri the line connects with the Namboku Line.

On 21 March 1982 the line was extended eastward by 7.4 km from Shiroishi to Shin-Sapporo, giving the Tōzai Line its eastern terminus and a connection to the JR Chitose Line. With the extension every train was lengthened to six cars, and additional 6000 series stock was built, bringing the fleet to twenty-four sets of 144 cars. A westward extension beyond Kotoni was also planned, but on 1 September 1987 the city decided to freeze it. Earlier the same year, on 22 March 1987, the Ōdōri–Nishi-Jūitchōme section had been closed temporarily, with substitute bus services, so that a connecting track to the new Tōhō Line could be built.

Around 1990 the automatic (ATO) operation of the 6000 series trains was discontinued and the line reverted to manual driving. The shelved western extension was revived during the 1990s: the project to reach Teine-higashi (a provisional name) was re-authorised on 13 February 1994, a railway business licence for the Kotoni–Teine-higashi section followed on 12 May 1994, and construction began on 16 March 1995. New 8000 series trains entered service on 18 August 1998, and on 25 February 1999 the final 2.8 km from Kotoni to Miyanosawa opened, giving the line its present western terminus. At the same time the 6000 series sets were lengthened to seven cars by inserting 8300 series intermediate cars.

From 2002 the ageing 6000 series cars began to be replaced by 8000 series stock, and 8300 series cars that had been added to the 6000 series sets were transferred to the new trains. Modernisation continued through the 2000s: English-language and advertising announcements began on the 8000 series on 27 September 2005, and from 2006 cars modified for one-man (driver-only) operation entered service. The last 6000 series trains were withdrawn on 30 August 2008, completing the changeover to the 8000 series, and on 1 September 2008 automatic operation under ATO resumed — roughly eighteen years after it had been suspended.

The SAPICA contactless smart card was introduced on 30 January 2009; platform edge doors, first trialled at Nangō-Nana-Chōme Station in 2008, were installed at every station by 3 March 2009; and on 1 April 2009 the Tōzai Line switched to wanman (driver-only) operation. A "Women and Children Comfort Car" was designated on each train from 13 July 2009. In fiscal 2023 the line averaged 237,500 boardings per day, roughly 99 percent of the fiscal 2019 figure, according to the Sapporo City Transportation Bureau.

19 stations tracked on the map, listed alphabetically. Select any to read its page.

• Bus Center-Maeバスセンター前
• Hassamu-Minami発寒南
• Hibarigaoka (Hokkaido)ひばりが丘
• Higashi Sapporo東札幌
• Kikusui菊水
• Kotoni (Sapporo Municipal Transportation Bureau)琴似
• Maruyama koen円山公園
• Miyanosawa宮の沢
• Nango nanachome南郷7丁目
• Nango-13-Chome南郷13丁目
• Nango-18-Chome南郷18丁目
• Nijuyonken二十四軒
• Nishi juhatchome西18丁目
• Nishi juitchome西11丁目
• Nishi nijuhatchome西28丁目
• Odori大通
• Oyachi (Hokkaido)大谷地
• Shin Sapporo (Sapporo Municipal Transportation Bureau)新さっぽろ
• Shiroishi (Hokkaido · Sapporo Municipal Transportation Bureau)白石

• 19714 October: the Sapporo city assembly approves construction of the first Kotoni–Shiroishi section.
• 197329 March: a groundbreaking ceremony is held for the Kotoni–Shiroishi section; work begins on 18 May.
• 197524 February: the city assembly approves the eastward extension from Shiroishi to Shin-Sapporo.
• 197610 June: the line opens between Kotoni and Shiroishi (9.9 km); four-car 6000 series trains debut and run under ATO automatic operation.
• 198221 March: the Shiroishi–Shin-Sapporo section (7.4 km) opens; trains are lengthened to six cars and the fleet grows to 24 sets / 144 cars.
• 198722 March: the Ōdōri–Nishi-Jūitchōme section is temporarily closed (with bus substitution) for Tōhō Line connecting-track work; on 1 September the western extension beyond Kotoni is frozen.
• 199413 February: the shelved western extension toward Teine-higashi is re-authorised; a railway business licence for Kotoni–Teine-higashi follows on 12 May.
• 199818 August: the new 8000 series trains enter service.
• 199925 February: the Kotoni–Miyanosawa section (2.8 km) opens, completing the line; 6000 series sets are lengthened to seven cars with inserted 8300 series cars.
• 2002The ageing 6000 series cars begin to be replaced by 8000 series stock.
• 200527 September: English-language and advertising announcements begin on the 8000 series.
• 200830 August: the last 6000 series trains are withdrawn, completing the changeover to the 8000 series; on 1 September ATO automatic operation resumes after about 18 years.
• 200930 January: the SAPICA smart card is introduced; 3 March: platform edge doors are completed at all stations; 1 April: the line switches to wanman (driver-only) operation.