The San'yō Main Line (山陽本線, San'yō-honsen) is a major railway line owned by JR Group companies in western Japan, connecting Kōbe Station and Moji Station, largely paralleling the coast of the Seto Inland Sea, in other words, the southern coast of western Honshu.

The name Sanyō derived from the ancient region and highway San'yōdō, the road on the sunny (south) side of the mountains.

A short section connecting Kitakyushu Freight Terminal also forms part of the Sanyō Main Line.

Prior to the opening of the San'yō Shinkansen, many expresses operated on the Sanyō Main Line as it served as a major transport corridor through Western Honshu and connecting to Kyushu.

The section between Kobe and Nishi Akashi was severely damaged by the 1995 Great Hanshin earthquake, and took ten weeks to repair.

[3] The Tatsuno Electric Railway Co. opened a 17 km (11 mi) 1,435 mm (4 ft 8+1⁄2 in) gauge line electrified at 600 VDC from Shingu-Cho to Aboshiko between 1909 and 1915 which connected at this station.