The line was initially proposed in 1971 by Japanese National Railways (JNR) as a link between the Katamachi Line, which connected Osaka to its eastern suburbs, and Fukuchiyama Line, which connected the city to its northwestern suburbs.
In 1988, after JNR privatized and split into Japan Railway companies, West Japan Railway Company formed a private-public entity called with the prefectural governments of Osaka and Hyōgo, and the cities of Osaka and Amagasaki.