The Osaka Loop Line (大阪環状線, Ōsaka kanjō-sen) is a railway loop line in Japan operated by the West Japan Railway Company (JR West).

All train services consist of eight cars, with distinctive orange color with white JR graphics on the front, rear and sides.

The completely loop shaped Osaka Loop Line is unable to use the "up" (上り, Nobori) and "down" (下り, Kudari) rail direction convention usually applied to JR lines.

Instead, the words "outer loop" (running clockwise) (外回り, Soto mawari) and the "inner loop" (running counter-clockwise) (内回り, Uchi mawari) are used to refer to the direction of the train, similar to the Yamanote line in Tokyo.

For purposes of rail registration of the line at the Ministry of Land, Infrastructure, Transport and Tourism,[2] the inner loop is considered "down".

Some operate over the complete loop, while some serve the eastern half between Osaka and Tennōji via Kyōbashi.

"Yamatoji Rapid" (大和路快速, Yamatoji Kaisoku) and "Regional Rapid" (区間快速, Kukan Kaisoku) trains originate at Tennōji on the loop, passing the loop as "inner" via Osaka, and after stopping at Tennōji after a complete circuit, exit the loop onto the Kansai Main Line and terminate at Kamo, Nara or Ōji.

Trains to the Hanwa Line, "Kansai Airport Rapid" (関空快速, Kankū Kaisoku) for Kansai Airport and Kishūji Rapid (紀州路快速, Kishūji Kaisoku) for Wakayama originate at either Tennoji or Kyobashi, and together with other types of rapid trains, operate on the inner loop via Osaka, pausing at Tennoji and then exiting from the loop.

113 series 4-car units were used for rapids of Shin-Ōsaka - Kii-Tanabe in early morning and late night.

The Osaka Railway merged with the Kansai Railway (関西鉄道, Kansai Tetsudō, also read as Kansei or Kwansai) in 1900, creating a single entity for the line from Tennōji Station to JGR Ōsaka Station.

The Tennōji to Sakaigawa Signal Box (between Taishō and Bentenchō, closed in 2006 when the branch to the port closed) section (south-western portion of the loop) was constructed for freight traffic by the JGR to the port area in 1928, connecting to a freight branch line of the Kansai Main Line, Imamiya – Naniwa (浪速) – Osaka-minato (大阪港, apart from the present Ōsakakō Station on the Osaka Municipal Subway Chūō Line) with a distance of 5.2 mi.

To complete the Loop Line, new tracks were constructed between Nishi-Kujō and Sakaigawa Signal Box by the then Japanese National Railways.

In 1964, operation as a complete Loop Line commenced with the opening of elevated double tracks around Nishi-Kujō.

The Tennōji – Shin-Imamiya section was quadrupled in 1968, to separate operations from the Kansai Main Line.