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Senmo Main Line

釧網線

The Senmō Main Line (釧網本線, Senmō-honsen) is a 166.2-kilometre railway line in eastern Hokkaidō operated by the Hokkaido Railway Company (JR Hokkaido), running from Higashi-Kushiro Station in the city of Kushiro to Abashiri Station on the Sea of Okhotsk coast.

It is a single-track, non-electrified line laid to 1,067 mm narrow gauge, and since the Shibetsu Line closed on 30 April 1989 it has been the easternmost surviving regional railway in Japan. Many tourist sights lie along the line: it skirts the Kushiro Marsh (Kushiro Shitsugen), passes near Lake Mashū, and runs along the Okhotsk shore where pack ice piles up in winter. In season it also carries the diesel "Kushiro Shitsugen Norokko" sightseeing train and the steam-hauled "SL Fuyu no Shitsugen."

Route of the Senmo Main Line · Hokkaido · Borders: MLIT

History

The corridor has a faint prehistory. In 1887 a private 1,067 mm gauge line, the Kushiro Railway, was opened to carry sulphur from a mine at Atsanobori to a refinery at Shibecha, about 48 km north of Kushiro; it closed some nine years later when the deposit was worked out. Decades afterwards part of that old formation was reused for the Senmō line's section between Shibecha and Teshikaga, but the Senmō line proper was a fresh project, constructed from both ends — southward from Abashiri and northward from Kushiro — to be joined in the middle.

The northern half opened first, and under a different name. On 15 November 1924 the Abashiri Main Line was extended from Abashiri (its first-generation station) to Kitahama, a stretch of about 11.6 km along the drift-ice coast. The rails reached Shari on 10 November 1925 and pushed on to Sattsuru on 14 November 1929, carrying the Abashiri Main Line name as they went.

The southern half came from Kushiro and was called the Senmō Line. It opened from Kushiro to Shibecha — roughly 48.1 km — on 15 September 1927. The line then reached Teshikaga on 15 August 1929 and Kawayu (today Kawayu-Onsen) on 20 August 1930.

The two halves were finally joined on 20 September 1931, when the gap between Sattsuru and Kawayu — about 22.8 km — was filled in. The Abashiri Main Line's section from Sattsuru to Abashiri was transferred to the Senmō Line, and the whole route became a single line. On 29 October 1936 it was renamed the Senmō Main Line, the name it has carried ever since, with "Senmō" formed from characters for Kushiro (釧) and Abashiri (網).

When Japanese National Railways (JNR) was broken up and privatised on 1 April 1987, the Senmō Main Line was inherited by the new Hokkaido Railway Company (JR Hokkaido) as a Category-1 operator, with Japan Freight Railway (JR Freight) holding Category-2 freight running rights over it. Those freight rights were abolished on 1 April 2002, ending scheduled freight on the line and leaving it a passenger-only railway.

After privatisation the line was promoted as a tourist route. The diesel "Kushiro Shitsugen Norokko" sightseeing train began running over the marsh on 24 June 1989, and a winter counterpart, the "Okhotsk Ryūhyō (drift-ice) Norokko," followed on 10 February 1990. JR Hokkaido also runs the steam-hauled "SL Fuyu no Shitsugen" between Kushiro and Shibecha (and on to Kawayu-Onsen) through the wetland in winter, a service it began on 8 January 2000. Since 16 March 2024 all of the line's regular trains have been worked by H100-series diesel railcars.

Stations on this line

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

Timeline
  • 1887The private Kushiro Railway, a 1,067 mm gauge line, opens to carry sulphur from a mine at Atsanobori to a refinery at Shibecha; it closes about nine years later when the deposit is exhausted, but part of its formation is later reused by the Senmō line.
  • 192415 November: the Abashiri Main Line is extended from Abashiri (first-generation station) to Kitahama (≈11.6 km), the first segment of what becomes the Senmō line, along the Okhotsk coast.
  • 192510 November: the line is extended from Kitahama to Shari (≈25.7 km), still as the Abashiri Main Line.
  • 192715 September: the Senmō Line opens from Kushiro to Shibecha (≈48.1 km).
  • 192915 August: the Senmō Line is extended from Shibecha to Teshikaga (≈25.3 km), reusing part of the old formation of the defunct Kushiro Railway.
  • 192914 November: the Abashiri Main Line is extended from Shari to Sattsuru (≈19.6 km) on the northern side.
  • 193020 August: the Senmō Line is extended from Teshikaga to Kawayu (now Kawayu-Onsen, ≈15.9 km).
  • 193120 September: the gap between Sattsuru and Kawayu (≈22.8 km) is filled, joining the two halves and completing the through route between Kushiro and Abashiri.
  • 193629 October: the through route is renamed the Senmō Main Line, the name combining characters for Kushiro (釧) and Abashiri (網).
  • 19871 April: with the breakup and privatisation of Japanese National Railways, the line passes to JR Hokkaido as Category-1 operator, with JR Freight holding Category-2 freight rights.
  • 198924 June: the diesel "Kushiro Shitsugen Norokko" sightseeing train begins running over the Kushiro Marsh.
  • 199010 February: a winter counterpart, the "Okhotsk Ryūhyō (drift-ice) Norokko," begins operation.
  • 20008 January: the steam-hauled "SL Fuyu no Shitsugen" begins service; it runs in winter between Kushiro and Shibecha (and on to Kawayu-Onsen).
  • 20021 April: JR Freight's Category-2 freight operation over the whole line is abolished, ending scheduled freight and leaving the line passenger-only.
  • 202416 March: all regular services on the line are taken over by H100-series diesel railcars.

Sources

Last updated 16 October 2026.

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