The is a railway line in Hokkaido, Japan operated by Hokkaido Railway Company (JR Hokkaido). It runs between Tomakomai Station in Tomakomai and Mukawa Station in Mukawa, along the coast of Hidaka Subprefecture.
Prior to storm damage in January 2015, which resulted in an indefinite suspension of services on most of the line, the line was 146.5 km (91.0 mi) in length, and trains ran a further 116.0 km (72.1 mi) to terminate at Samani Station in Samani. This section was formally closed on 1 April 2021 and permanently replaced by bus service. The closure of this section made the line the second shortest in Japan to be classified as a "main line", at just 30.5 km (19.0 mi), after the Rumoi Main Line's length of 14.4 km (8.9 mi). After the Rumoi Main Line's closure on 1 April 2026, the Hidaka Main Line became the shortest main line in Japan.
All regular trains are local trains, which stop at all stations.
The first section was opened in October 1913 by the , operating between and (present-day ). The section between Sarufuto and was operated by the . Both lines were light railways with a track gauge of .
The lines were nationalized on 1 August 1927, and merged into one, becoming the Hidaka Line. The track gauge was widened to between Tomakomai and Sarufuto on 26 November 1929, and between Sarafuto and Shizunai on 10 November 1931. The line was extended from Shizunai to on 15 December 1933, to on 24 October 1935, and to Samani on 10 August 1937.
With the privatization of JNR on 1 April 1987, the line came under the control of JR Hokkaido.
Following storm damage between Atsuga and à Âkaribe stations on 8 January 2015, rail services had been suspended on the 116.0 km (72.1 mi) section beyond Mukawa station, with buses providing a substitute service. Further damage was caused to the line by Typhoon 17 or Typhoon Kilo on 12 September 2015, and no date had been set for the resumption of rail services beyond Mukawa. In December 2016, JR Hokkaido announced that it had abandoned plans to reopen the suspended section of the line, and was in discussion with the local governments involved.
Due to low ridership and very high repair costs, including coastal defences between Atsuga and à Âkaribe, JR Hokkaido held several meetings with the seven towns along the suspended segment of the line, suggesting to abandon plans to restore the line and replace it with a bus service. In November 2019, six out of the seven towns agreed to replace the damaged section with a bus service. However, the town of Urakawa still strongly requested for the whole line to be restored; Urakawa's mayor reasoned that it would still take a while for the 'developing' Hidaka Expressway to reach the town, therefore it being necessary to retain the rail service.
In September 2020, after five years of meetings and discussions, many of which involved extensive arguments and disagreements, all seven towns eventually agreed with JR Hokkaido to abandon the line's damaged section and replace it with a bus service. The 116.0 km (72.1 mi) section was formally closed on 1 April 2021.