The is a 26.3 km railway line owned by the Heisei Chikuhà  Railway. The line runs west along the Ima River from Yukuhashi to Tagawa, all within Fukuoka Prefecture.
The line was first built in 1895 by the , which was merged in 1901 with Kyushu Railway. It was an important railway line to transport coal between the Chikuhà  coal mine with in Kanda, north of Yukuhashi. Kyushu Railway was nationalized in 1907 and was merged into Japanese Government Railway, where it was named the Tagawa Line. In 1942, the line was extended south from Ita Station (now Tagawa-Ita Station) to Hikosan Station. The portion between Hikosan and Soeda Station was later reorganized into the Hita Line (now Hitahikosan Line) in 1956, and the section between Soeda and Ita was also merged into the same line in 1960 to form the current Tagawa Line.
Between 1899 and 1973, a short freight-only branch line ran north from Kawara Station (now Magarikane Station) to Natsuyoshi.
Ridership suffered with the decline and closure of the Chikuhà  coal mine. Therefore, JR Kyushu, the successor of Japanese Government Railway, privatized and transferred the Ita Line, Itoda Line, and Tagawa Line to the newly founded Heisei Chikuhà  Railway in 1997.
The line is not electrified and is single-tracked for the entire line. Some services continue past Tagawa-Ita Station on the Ita Line to NÃ Âgata Station.
The Tagawa Line runs through many historical sites, including the , the oldest railway tunnel in Japan, and the , an old brick arch bridge. Both sites were registered as national cultural heritage sites in 1999.
All stations are within Fukuoka Prefecture.