The Kaikyō Line (海峡線, Kaikyō-sen) is an 87.8 km (54.6 mi) railway line operated mainly by the Hokkaido Railway Company (JR Hokkaido).

The line connected Naka-Oguni Station in Sotogahama, Aomori, through the Seikan Tunnel between Honshu and Hokkaido, to Kikonai Station in Kikonai, Hokkaido.

As all regular passenger services are Shinkansen, the Kaikyō Line is normally used only by freight trains.

Originally the line ran both freight and passenger trains; the latter included daytime limited express Hakuchō and night train Hokutosei.

Three of the stations on the Kaikyō Line, Tappi-Kaitei, Yoshioka-Kaitei, and Shiriuchi, were closed on 15 March 2014 due to construction work connected with the Hokkaido Shinkansen, which opened on 26 March 2016.